Add in initial generic cloudinit userdata template and snippet

This is the in initial import of generic cloudinit userdata template and snippet used in EC2 to modify the hostname on instance initial boot.
I have tested this using Foreman 1.4.1.
The code assumes that CloudInit is included in the ami / image and uses CloudConfig commands.


References for the code cane be found here:
http://cloudinit.readthedocs.org/en/latest/topics/capabilities.html

Command to call back to Foreman to confirm build is complete.
http://cloudinit.readthedocs.org/en/latest/topics/examples.html#call-a-url-when-finished

I placed the main file userdata_cloudinit.erb in a new cloudinit directory as I did not think that it should go into kickstart, etc.

I was told by gwmngilfen that I should go ahead and submit the changes and then we could discuss in the details in the PR.  

I have not made any changes to any other files, these are only additions to foster feedback.
I suspect changes will need to be mde to https://github.com/theforeman/foreman/blob/develop/db/seeds.d/07-config_templates.rb to pull the files in for usage on install of the foreman system.