Repost: Refactor service module to use subclasses like user module.

* Basically the moving parts from the original service module arranged in
  subclasses.
* General structure and helper methods comes from the user module.
* Less forgiving to unsupported platforms: it requires a subclass per platform.
  (This makes it easier to work on one platform without having to think about.
  what other platform might be affected in unexpected ways).
* Now has basic OpenBSD support.
* Solaris support needs to be added.

Thanks to @dhozac for general advice and Linux testing.
Thanks to @bcoca for clearing up some FreeBSD questions.

module_formatter: re-instate code

Implemented more virtualization types

DOCUMENTATION: yum (moved version to added)

Otherwise, a host in two groups, A and B, using a variable defined
in group A and all will get the value of all, as B's variables will
include the all variable.

Partially fixes #1647.

global_vars has higher precedence than inventory. Putting the all
group's variables into it overrides all other groups and hosts.

Partially fixes #1647.

Fixes all not being processed, as well as the order of the variable
precedence

Fixes #1567.

I added all known virtualization types from the virt-what project. However, the few virt types that rely on cpuid information have not been implemented lacking native python cpuid access. (hyperv)

DOCUMENTATION strings

Broken by the move from utils.py to utils/__init__.py

Allows using -e ansible_ssh_port=foo and have it apply to all actions.

Make the default an empty string

Seems a bit strange I have to set a default in two locations.

Use runner's basedir as cwd for -c local

Provide a proper error when the remote_port is not an integer

Allow the remote port to be templated per play

As reported on the mailinglist, the user received a ValueError when the port number was not templated (fixed in #1649) and therefore it was not an integer. This change will catch the exception and provide a proper error so it is more clear.

This was requested on the mailinglist and seems useful.