feat(internal resources) - add the capability to declare some resources internal

Internal resources can be used only for data manipulation using the datalayer.
We need this so we can decouple from flask.request object in Eve-Elastic extension. When we have to do an internal call against Eve-Elastic we won't have to create a test_request_object.
I'm referring to this commit in the extension: https://github.com/petrjasek/eve-elastic/commit/b7ef00f17dbfa549d12fdcffcdd0911d455e523e