REVIEW: [NX-485] remove embedded dependencies from (most of) Nexus

Some embedding remains in a few plugins - will be removed asap, just wanted to get this up for review first. Also the nexus-extender now uses OSGi metadata to decide which bundles should be started in what order, and what scanning they require (JSR330, Plexus, WebResources, etc.)

http://bamboo.s/browse/NX-OSSF180-7 :white_check_mark: 
Just curious: Where are we using Snappy? Last time I met snappy was in relation to KZ....