API v2 migrated to new permissions model

API v1 migration to new permissions model

Set authorizer filter for controllers

Various typo errors on API controllers corrected

Remove role validator to make migration script pass

Authorizer in application controller

@authorizer goes in application_controller and it is called from the
views, since it's a helper method. This saves us from having an
after_filter or @authorizer defined everywhere.
However I believe this might be a security risk and Authorizer should
be a singleton class.

Use @smart_proxies over @proxies for consistency
Refactor authorized scope in controllers