Release version 0.6.0

Changelog:

• This release has a new Internal Agent interface which is not backwards compatible. For details and guides about the new interface see AgentDeveloperGuide.md. The reason relates to the problem of having agents "responsible" of O-DF paths in a way that they can reject a write request (e.g. failing to control a device). More details about this will be written in near future.
• Bug fix related to callback connection pool. Should fix problems such as server not sending callbacks.

Note: We have currently problems generating java api documentation, we will add the api docs as soon as we can. In the meanwhile, you can use scaladocs which have only different syntax but is usable with java code also. (Scaladocs can be found in the release package at /html/api/index.html)

Edit: The builtin example agents contains errors so they don't work correctly. The documentation and files on github are corrected but rename the classes if you copy the examples to avoid running the broken builtin agents. This will be fixed in next release.