Remove unused rubygem-less, less-rails build deps

Looks like this was added back in 1.2 when we went to SCL, but core doesn't use it.  This may replace #390 (sorry @ehelms!).

Builds of foreman, hopefully proving we don't need it:
http://koji.katello.org/koji/taskinfo?taskID=170857 f19
http://koji.katello.org/koji/taskinfo?taskID=170858 el6
http://koji.katello.org/koji/taskinfo?taskID=170861 el7