Remove fabric/fabric-karaf-overlay module
datastore configuration: now merges eventual config found in .cfg with params provided at Karaf prompt
 #2676 Wrong usage of felix.obr.version
Clean use of maven
  * put aether/maven in its own bundle
  * use it for agent and proxy
  * remove old modules (insight-maven, maven-util)
Delete deprecated fab
Abstract a bit more the use of the MavenResolver
Export the MavenResolver as a service, use it for the maven proxy, trim down a bit the dependencies of fabric-maven