Clean up for the JSON API work

The "internal" API only store dict, rather them store xml, this makes flexible to others APIs to be implemented w/o changing the core of the master.

It makes slapos.slap.slap only used on SlapTool context, releasing the internal API on having it, so it won't become a dependency anymore.

The approach is deprecate the usage of SlapTool as soon clients relies on a different API.

TODO:

• Make Tests Pass
• Clean up code (the creation of Compute Node and Compute Partition specially)
• Cache the Compute Node XML in addition to the Dict (else the system will become too slow)