Add support for neutronclient

The quantum_* modules will now try neutronclient first, and fall back
to quantumclient. If that fails, error out.

The code now references neutron instead of quantum in all internal
cases.
Specify internal_network_name

This allow one to specify a specific internal network name for the case
where there is more than one nic on an instance. Without this, the list
of ports may not return the correct order. Therefore, it is necessary
to specify the exact internal network to attach the floating ip to
Spiff up the 'Developing Plugins' page

* Add more cross-documentation references
* Fix some broken links
* Add links to github/source code references
Merge pull request #5322 from bcrochet/neutron-fip-select

quantum_* modules: Neutron name change, keeping backward compatibility
Remove unused variable from authorized_key
Allow keystring passed to authorized_key to contain blank lines and comments
Added ANSIBLE_SSH_PIPELINING option to enable/disable pipelining support

Pipelining will be disabled by default, since it requires users remove
the 'requiretty' option from the servers sudoers configuration.
Fixes #5631 Return a unique list of hosts when joining groups
Add support for Scientific Linux for hostname module

hostname module was lacking support for Scientific Linux, this commit adds it.
Fixes #5656 quote values with multiple columns before calling
the sysctl command. Calling sysctl should also not be true by default
Merge pull request #5655 from scottgilbert/devel

Allow keystring passed to authorized_key to contain blank lines and comments
Merge pull request #5658 from rishid/devel

Add support for Scientific Linux for hostname module
Removing colon from example failure message

The example failure message was given as - fail: msg="Bailing out: this play requires 'bar'"

The colon in the example causes a YAML compile error, so I am replacing it with a '.'
Merge pull request #5665 from Taytay/devel

Colon in example failure message causes a YAML compile error
Fixes #5661 Handle null values for sysctl parameters
Make synchronize module work better with local transport, fix #5668
Merge pull request #5586 from tbielawa/spiff_up_plugins

Spiff up the 'Developing Plugins' page
fix str format error due to missing '%' in sysctl module
Merge pull request #5672 from simonz05/patch-1

fix str format error due to missing '%' in sysctl module
Merge pull request #5669 from mscherer/fix_synchronize_local

Make synchronize module work better with local transport, fix #5668