Fixes missing split_hosts function import on mysql

The mysql plugin didn't have the proper import for
the split_hosts function which was only excuted when
neutron is disabled.

Change-Id: Ibf30815b5ace6e83d90dd6b29dfe5b0621fc70cc
Added the help_url pointing to RH doc

Fixes: rhbz#1030398

Change-Id: I6b7637331a99059bea96f0a83e75c1807c784890
Merge "Added the help_url pointing to RH doc"