Extract files loaders and scaffold to separated libraries

[javierbrea]

In order to optimize the core for a programmatic usage and to make the system more scalable, it is desirable to extract the current files loaders into a plugin.
The scaffold should also be extracted from the core package. A method for creating a scaffold file could be added to the config pacakge, and the part creating the routes and collections scaffold should be moved to the new files loader plugin.

This is related to #375 , and could be made probably as a part of the upcoming changes to adapt the whole system to the new data model.