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
Attempt #2 to cause yum to fail on invalid url
Spiff up the 'Developing Plugins' page

* Add more cross-documentation references
* Fix some broken links
* Add links to github/source code references
Fail yum on invalid url with .rpm suffix
Do not log the rax api_key argument in module invocation
Merge pull request #5636 from sivel/rax-no-log

Do not log the rax api_key argument in module invocation
ec2_elb module: Minor improvements to documentation

ELB(s) cause a weird formatting behaviour - it appears as EL**s**
Added choices documentation to the state option
Merge pull request #5640 from willthames/ec2_elb_docs

ec2_elb module: Minor improvements to documentation
Reverting paramiko_ssh/alt changes from yesterday
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 '.'