apipie documentation of actions defined in a concern

Apipie now supports defining actions defined in module by including
`Apipie::DSL::Concern`. Some substitutions are preformed while including the
documentation in each controller, so that instead of paths like
`/:resource_id/:id`, you get `/oraganizations/:id` or
`/locations/:id` respectively. Also param names and descriptions are treated
this way. See https://github.com/pajk/apipie-rails#concerns for more details.