Check file exists instead of relying on the exception. Leave the exception catch in, in case the file is deleted or some other issue crops up

Changing to read from a file pointer instead so that an exception is thrown if the file doesn't exist

1. Passing the module to the various functions so that they can use module.fail_json and module.exit_json methods inside.
2. Because of point 1, install and remove methods do not return anything. Instead, they use the module functions itself.
3. Move the import statement (for apt and apt_pkg) inside main function so on import error, we can use module.fail_json to print the error.

This drops the branch option.  The version option is overloaded
to mean either a sha1, branch, or tag.  This also adds the option
'remote' which defaults to 'origin'.
clone() was simplified by removing the checkout operation.  That
happens later when switch_version() is called.

Added the methods get_branches(), is_remote_branch(), and
is_local_branch().  get_branches() returns an array listing all
of the branches for the git repository.  is_remote_branch() checks
whether the arguments supplied correspond to a remote branch.
Similarly, is_local_branch() checks for a local branch.

The pull() method now checks to see if it is on the desired branch.
If not, it checks out the requested branch and then does a pull.
This should keep issue #604 still fixed.

switch_version(), formerly switchver(), looks to see if it is
checking out a branch.  If a branch, it checks it out with the --track
option.  This type of checkout was in pull() before.

Updated pull, clone, and switch_version to return (rc, out, err).

Port command module over to new common code.  Notice that this has to subclass AnsibleModule -- this should be the only
one that has to do that.

Save the transfer of the module file for new style modules, because we can inject the arguments into the modules.

Module consumers using the API don't have to know how this works.  base64 stuff is only there
because escaping a docstring inside a docstring was a bit of a challenge :)

Tweaking daisychain internals to allow get_url to modify the path destination when downloading to a directory.
Minor module refactoring.

	get module (with new module-magic-code!)
	Usage: ansible -m get -a "url=http://xxxxxxx  dest=fileordirctory"
	all cleanups as per @mpdehaan's suggestions
	add daisychain
	added example playbook (get_url.yml) with URLencode example

Do not switch to master branch in pull()
Add --track to git checkout, when checking out a remote branch to track.

By defining a main function here, and including it ahead of the boilerplate insertion symbol, tracebacks are
now accurate with respect to the main function, but may include lines not in the original file.  A lot better
than before, where they were offset.

get_interfaces() updated to read /proc/net/dev.  This means it no
longer provides only interfaces that are up.

get_iface_hwaddr() updated to read from /sys/class/net/<iface>/address.

Added get_interface_facts() to pull in mac address and interface mtu.
Can be used later for additional interface-facts.

Added get_ipv6_facts(), which reads from /proc/net/if_inet6.

get_network_facts() renamed to get_ipv4_facts().  It still calls
ifconfig to determine ipv4 facts.

The processor fact doesn't exist in LinuxVirtual.  Read /proc/cpuinfo
and check if it is QEMU.

The Facts class and subclasses no longer take a dict argument for
instantiation.  populate() now returns self.facts.
Other changes:
- Facts.__init__() takes over most of the work from populate() so that
  subclasses can benefit from its knowledge.
- Drop setting unknown facts to 'NA' in __init__() in various
  subclasses.
- Check for presence of facts in get_virtual_facts()
- Update ansible_facts() to use facts.update(<classname>().populate())

This changes and organizes facts into a base class Facts and several
sub classes that implement the necessary functionality.  The classes
are:
- Facts: base class.  Implements basic facts that should be common to a
  number of platforms.  It is also where SSH keys and SELinux facts are
  set.
- Hardware: A subclass of Facts that should be further
  subclassed per platform for CPU, memory, and related facts.
  - LinuxHardware: subclass of Hardware for Linux platforms
  - SunOSHardware: subclass of Hardware for SunOS platforms
  - FreeBSDHardware: subclass of Hardware for FreeBSD
- Network: A subclass of Facts that that should be further
  subclassed per platform for IP, both IPv4 and IPv6, information.
  - LinuxNetwork: Currently only implementation for determining network
    facts.
- Virtual: A subclass of Facts that that should be further
  subclassed per platform to determine virtual environment facts.
  - LinuxVirtual: Currently only implementation for determining virtual
    facts.

If facts are needed for additional platforms, one of the above classes
(eg Network) can be further subclassed and implement the necessary
functionality.

In addition, it fixes get_network_facts() to work on Fedora17.  That
broke due to changes to ifconfig output.