ECF 3.13.7 Oxygen: Maven and Python OSGi Services

ECF 3.13.7 has been released as part of the Oxygen Simultaneous Release.  ECF's work recently has emphasized it's implementation of OSGi Remote Services, and the 3.13.7 continues this emphasis.

Highlights:

1. ECF has multiple distribution providers, and most have been moved to Maven-based builds
2. Remote Services/RSA is now available via Maven Central, and the Karaf Feature Install uses Maven install.
3. A new distribution provider that allows Python code as OSGi Services.   See this tutorial for a description.
4. Many bug fixes and small improvements