Change ohaisolo and poshohai domains

This replaces the URLs for Ohai-Solo and Posh-Ohai to use a
rackspace.com domain in order to help properly identitfy the source of
the packages and prevent confusion to users on what is being done.

In the future, this URL should be fully customizable to allow for
someone to host their own Ohai-Solo/Posh-Ohai packages if they so
choose.

Closes-Bug: #1386745

Change-Id: If2b58846eb47c550614a94d73bdf33ac79ff9cf5