Implements drilldown view for search

This is a POC of the new master/detail view as proposed by [Nexus-7612](https://issues.sonatype.org/browse/NEXUS-7612). It has _only_ been applied to the search view, none of the other master/detail views are affected.

I think this is a big improvement over the existing behavior, but not sufficient in and of itself to warrant closing [Nexus-7612](https://issues.sonatype.org/browse/NEXUS-7612). @jdillon @adreghiciu, what do you think? Merge or no?

Before:
http://monosnap.com/file/hjQMD0mRlILEP2lb6UPttNs2divh5N

After:
http://monosnap.com/file/7Sen9mS3LiWjnHMRKehD3bJSfwOo0r
Resolved.