Add a plugin that permit to use ansible for lxc system, using libvirt

Using -c lxc and the domain name as hostname, this permit to manage a whole
range of container, provided they are managed and created by libvirtd.
add a inventory script that go with the lxc connexion module
[digital_ocean] Don't die when the id parameter is missing

It's okay for this to happen now, because we might move on to the name parameter
if unique_name is enabled.
Add basic domain handling to digital_ocean cloud action
[digital_ocean] revert original module and add one new module for each command
[digital_ocean] Remove command usage from digital_ocean_ssh examples

I seem to have forgotten to do this in my last commit.
Add packaging module for Gentoo Portage.

This is in no way comprehensive enough to cover all use cases, but hopefully
is sufficient to cover the common ones.
Added metadata support to s3 module
New module: ec2_ubuntu_ami

This module will retrieve the AMI of the most recent official Ubuntu
EC2 image for a given Ubuntu release.
Rename to ec2_ami_search
Genericize module to support multiple distros

Make the module implementatino more generic to support distributions
other than Ubuntu in the future.

Adds distro as a new parameter.
Allow for reuse of allocated but unassociated Elastic IPs.
Added replace module

Heavily based on existing lineinfile module, but where it literally tests a regexp against
*each individual line* of a file, this replace module is more analogous to common uses of
a `sed` or `perl` match + replacement of all instances of a pattern anywhere in the file.

Was debating adding `all` boolean or `count` numeric options to control how many
replacements to make in the destfile (vs currently replacing all instances)

Noted use of MULTILINE mode in docs, per suggestion from @jarv
Added module to handle nova security groups

This module is loosely based on ec2_group module.  However, rules are
handled slightly differently.  Specific rules are able to be removed vs
removing all "rogue" [1] rules.

[1] Rogue rules are existing security group rules, which are
    not included in the `rules` dict.
Additional idempotent states for virt module: "destroyed" and "paused"
Added ability to manage nova floating IPs

This module is based off the ec2_eip module, but accounts for pools,
which is openstack related functionality.
Made a few canges as I learn more about modules

* Set check_mode to False, am not supporting this ATM.
* Cleaned up delete/create() into single update().
* Return the group_id if created or found so tasks can be chained.
Rename digital_ocean_ssh to digital_ocean_sshkey per https://github.com/ansible/ansible/pull/4315#issuecomment-30286556
Adding absent condition for to the wait_for module
Adding 'export' option to subversion module (to export instead of checkout)