fixes #6244

Add credential parameters to the GCE modules.

In order to simplify the workflow with the GCE modules, it's now
possible to add the parameters and project name as arguments to the
various GCE modules.

The inventory plugin also returns the IP of the host in
`ansible_ssh_host` so that you don't have to specify IPs into the
inventory file.

Some update to the documentation are also added.

Closes #5583.

Update intro_installation.rst

Fix broken Ansible Tower link.

error in ubuntu install instructions

setup: Fix KeyError: 'ipv4_secondaries' (issue #6274)

Fix wrong module name for exception in nova compute

Fixed Links

Link to guru page was not rendering correctly on http://docs.ansible.com/faq.html.
Link to readme returned 404.

Update README.md

ansible depends on sshpass as well.

  failed: [127.0.0.1] => {"failed": true, "parsed": false}
  invalid output was: Traceback (most recent call last):
    File "/tmp/ansible-tmp-1393950384.39-102240090845592/nova_compute", line 1328, in <module>
      main()
    File "/tmp/ansible-tmp-1393950384.39-102240090845592/nova_compute", line 241, in main
      except exc.Unauthorized, e:
  NameError: global name 'exc' is not defined

Removes pluralization of manager tag attribute.

Add comment about mod_admin_extra

Fixes issue #6027.

Synchronize .deb package version with VERSION file

Add support for checking host against global known host files.

The effect of this is that before this fix if files are spread across the known_hosts file but not in the ~/known_hosts file the hosts will execute sequentially. This PR augments the functionality so that all of the knowns hosts will execute in parallel. 

Fixes templating of ansible_ssh_host for delegates.

Tested that this works. Confirmed.

Fix incorrect use of copy() on list, causing a traceback

Avoid range selection on empty groups

Update CONTRIBUTING.md

docsite no longer has a subdirectory latest.

minor typo in playbooks_variables.rst

This prevents a traceback when the group is empty.
Fixes #6258

Another minor typo.

so so, this should probably be fixed!

Merge pull request #6256 from angstwad/changes_changes-yo-dawg-i-herd-you-like-changes-so-commited-some-changes-into-changes-so-you-can-diff-while-you-diff

Add note about su support in CHANGELOG