Fakeapi refactoring

Removing knowledge of fakeapi from production code.

Summary of the changes:
* all fakeapi files moved out of the spec folder, to communicate clearly that they are not used for tests, and to serve them as assets (in development) without serving all the specs
* removed conditional logic to load fakeapi
* fakeapi specific configuration defined in development.rb
* javascript and ruby stubbing controlled using a single environment variable, USE_STUB_API