Remove org.eclipse.m2e cruft from cassandra pom

I added a <pluginManagement> section to the titan-cassandra pom with
configuration for the "m2e" maven plugin for the eclipse IDE.  After
further consideration, I decided that doesn't belong in master.  Our
poms are already complicated enough without adding IDE-specific "bonus
configuration" on top of maven's own fundamental complexity.
Log statement change

The commit ab505b835cc5d17a1b53ae10677b879cfe71bcc3 added a WARN log
statement that really should be no higher than INFO at the most.
Changed it to DEBUG.
Cassandra test class simplification

* Pulled duplicated code in CassandraStorageSetup into a helper method

* Removed unnecessary use of an ExecutorService and Runnable in
  CassandraDaemonWrapper.  CassandraDaemonWrapper now calls
  CassandraDaemon's main method directly.
InternalAstyanaxKCVTest import cleanup