v0.15.0

• complete rewrite of the Web UI, it is now based on Angular JS,
  Velocity is no longer needed, it is reponsive so it looks well on
  smart phones and tablets
• the REST server now supports: channel scan, changing the
  configuration, basic authentication over TLS/SSL
• OpenMUC now requires Java 1.7 instead of Java 1.6
• added new aggregator driver that be used to easily log average
  values
• added REST driver that can access other OpenMUC devices that have a
  REST server
• improved ASCII logger