Fix ppa syntax in apt_repository module doc

ansible-doc: print Notes heading only if there are any

pip module improvements

Tweak docs for correct paths and filenames for ec2 inventory

- Do not silently ignore malformed pip requirements files.
- Properly reports changed when removing packages.
- "latest" i.e. --upgrade is *not* incompatible with requirements files.
- Less branchy, simpler logic.
- Removed pointless variable "initializations", Python doesn't need that.
  Other code simplifications.
- Fun fact; pip install is (kind of) case insensitive, pip freeze is not.
  So, 'sqlalchemy' will be reported as installed by install, but missing
  by freeze.

The perhaps controversial change and the one that led to finding /
fixing above issues...

Instead of adding command parameters 'index', and 'find', and 'mirrors',
and etc.  Added 'extra_args' which are passed onto pip.

The use case for --index-url is having a private pypi repo, like
http://pypi.python.org/pypi/localshop, to which you publish private
packages.  I'm sure most every pip option has a use case for someone.
extra_args handles all those. Can reserve ansible command parameters for
the most common.

Tested with pip 1.1.

if user has manually installed an intermediate version - don't ignore it...

make --list-hosts expand out extra vars in the hosts: field

The example for using a ppa had the wrong syntax.

Ironically, the correct syntax is illustrated in a comment on line 23.

CLI: ansible-doc rebased

added support for scheduling downtime for all services on host

supervisorctl: document the 'present' option

Fix "NameError: global name 'name' is not defined" exception

Further refine remote branch tracking in b1ec6e81

Move operations that are dependant on a remote branch under a if
is_remote_branch() conditional.  While at it, remove assignment to cmd
string in same block that wasn't used when calling _run().

Fix git module to update branch to latest when using version=<branch>

The git module would not pull in updates to a branch when
version=<branch>.  This updates that block to checkout the branch
and then do a git reset --hard <remote>/<branch>.  This
should now track updates to a branch.

Import errno to avoid 'NameError: global name 'errno' is not defined'

I hit the following exception because errno is referenced but not imported.

```
fatal: [system01] => failed to parse: Traceback (most recent call last):
  File "/root/.ansible/tmp/ansible-1354644532.37-246102819320352/copy", line 782, in <module>
    main()
  File "/root/.ansible/tmp/ansible-1354644532.37-246102819320352/copy", line 117, in main
    module.atomic_replace(dest_tmp, dest)
  File "/root/.ansible/tmp/ansible-1354644532.37-246102819320352/copy", line 772, in atomic_replace
    if e.errno != errno.EPERM:
NameError: global name 'errno' is not defined
```

Template override

Further tweak how to find pip in virtualenv on centos/redhat/fedora

In a virtualenv, pip is called just pip.  This fixes the pip module to
search for the virtualenv pip first before trying the pip-python and
python-pip variants.  Without this, pip module would not install to the
virtualenv when that parameter is provided.

Make use of mirrors in pip module configurable with use_mirrors option

Older versions of pip (anything less than 1.0?) do not support
--use-mirrors flag.  This makes it configurable.  Default is yes.

Implements multiple interpreter overrides

Allow inventory scripts to define groups of groups and group vars

Fix pip module to check if requirements already installed

This updates _is_package_installed() to accept a requirements file
as an argument.  This is used later in main() to check if python libs
specified in a requirements file are already installed.  I updated
main() to consolidate the handling of install/uninstall in a single
block.  This should help if someone wants to remove packages specified
by a requirements file.

Updated ansible version to align with RPM package