Remove runtime dependency on bootstrap-sass, asset precompilation only

Two more RPMs removed from the default install.  They're already in the foreman-assets deps, but are unneeded at runtime when we ship precompiled stylesheets.

http://koji.katello.org/koji/taskinfo?taskID=175198 f19
http://koji.katello.org/koji/taskinfo?taskID=175200 el6
http://koji.katello.org/koji/taskinfo?taskID=175202 el7