fixes #2231 - hostgroup deletion is restricted to hostgroups without children

fixes #2728 - POST /api/hostgroups does not accept ancestry

set apiadmin user in headers before api controller tests

This commit adds most of the functionality required for API v1

The overall goal was to extract the existing JSON response
overall controllers, and to move them to a seperate name space.

• documentation was added to all requests (available under /apidoc)...