[zookeeper] Migrate ZK duties to Curator

[zookeeper] Finish migration to Curator and add tests

[zookeeper] Fix borked rebase

Conflicts:
	pom.xml
Fix for dependency invocation handling, tests.

This fixes 2 things:
 - don't try to restore invocation counts from ZK state (as they may be
   wrong due to missed status updates).
 - reset the invocation counts any time a dependent job starts.

Also added more tests around dependencies.

Conflicts:
	pom.xml
Exclude netty (from ZK) in pom.xml.