Revert "ptables - validation for OS families"

This reverts commit b33f440434244fff5af7d036b43b6068c1b74e08.

This patch does not really work, and was merged with insufficent
tests... sorry about that.

ptables - displaying os_family and layout in api show and list

ptables - validation for OS families

Using Apipie versioning features and Maruku for markdown

Apipie switched from Redcarpet to Maruku to avoid crashes of the C
Extension. No further need of compiling anything to get markdown support.

API now allows for search of usergroups

refs #2141 - ensures no duplicate trends are created

include nested host routes in the api documentation

fixes #2141 - Trends grahs issue

fixes #2154 - "Foreman" link in main navigation should link to dashboard

fixes #2161 - Cannot delete a host if the compute resource VM is already deleted