DO NOT MERGE fixes #4181 - change API V2 functional POST/PUT tests and apipie definitions to reflect unwrapped params (no root node)

The driver behind changing the functional tests (POST/PUT) is to update the API v2 docs on theforeman.org to show no root node
The nested path roles/:role_id/filters caused a test failure for create a filter, so this fixes it by removing the route in the test environment.

Note, that "path generated" params are not wrapped by Rails. For example

POST /api/architectures/1/operatingsystems

has a parameter {"architecture_id": 1} but it is not wrapped in the "operatingsystem" root node.  Here is a good explanation
http://stackoverflow.com/questions/12066607/why-doesnt-rails-parameter-wrapping-include-things-globbed-from-the-uri

Note, I also tried to change the order of the routes to have `/roles` listed first before `/roles/:role_id/filters` but it didn't help.