Repository refactoring

[m-s-]

We are refactoring our repository interface to push and pull packages. Currently we only support local and remote folders, and the implementation is spread through 3 different approaches and has leaked into the CmfPackage objects.

We want to have a single interface for the source (and target) of a package that can support a variety of protocols.

Initial back-of-the-napkin design includes:

• having a single point in the CmfPackage object pointing to its source. This source should be a repository object that implements a stable interface (let's call it IRepository)
• each protocol should implement its own Repository class
• the interface should provide some standard methods. We need, at least:
  • get
  • publish
  • contains
  • ...
• we need a factory that can choose the correct protocol from the information in repositories.json