Minor SQL optimization to hosts page

fixes #272 - add a warning if there is a clock drift between the client and foreman

migration might fail if medium does not have an opeartingsystem - refs #236

fixes #269 - Remove activescaffold from audits page

Fixes #212 - Remove AS from facts

fixes #268 - 500 Error on "All Puppet Classes"

fixes #236 - Installation media are now usable with more than one operating system.

Fixes #265 - improved preseed template and more complicated partitioning scheme for Debian-based distributions.

fixes #264 - Overview of host's puppet classes should be sorted

Fixes #262 - Architecture selection on create/edit operating system form