TopN performance improvements

Re-factor scanAndAggregate in PooledTopN

* Loops are now a little bit tighter when looping over aggregates. This will hopefully assist in loop execution optimization.
* Pre-calculated the aggregate offsets instead of shifting them during runtime.
* Cursor loop could use some TLC, but would require a massive refactoring on how TopN queries are executed.
  * Any potential modifications to query workflow need to account for Stream vs Batch data, and that not all data will be array backed that comes in.

Change data storage type in TopNNumericResultBuilder.

  * Use PriorityQueue to store
  * Checks to see if should even bother adding to Queue before adding.
  * Re-orders Queue on build() call.
  * Ideally the order would be directly preserved on build(), but this is a close second.

Updates to CompressedObjectStrategy to support more compression types

 * Compression types are not yet dynamically configurable.
 * Added a benchmarking system for topN to test the compression
 * Updated pom.xml to include junit benchmarking
 * added an Uncompressed option
Merge branch 'druid-0.7.x' of github.com:metamx/druid into druid-0.7.x-fastTopN-rebase
Removed negating comparator in TopNNumericResultBuilder
Merge remote-tracking branch 'origin/druid-0.7.x' into druid-0.7.x-fastTopN-rebase
Changed TopNNumericResultBuilder imports to not use package.*, but instead pulls all in explicitly
Removed CompressedObjectStrategy from this pull request. will submit a new one later
Update dim name comparator in TopNNumericResultBuilder to better handle nulls
Pre allocate LinkedHashMap in TopNNumericResultBuilder
Added comments in TopNNumericResultBuilder
Moveed processing/pom version into master pom
Moved pom version for reals this time
Merge branch 'druid-0.7.x' of github.com:metamx/druid into druid-0.7.x-fastTopN-rebase
Make some variables in PooledTopNAlgorithm final
try to benefit from out of order execution
Merge remote-tracking branch 'origin/druid-0.7.x-fastTopN-rebase' into druid-0.7.x-fastTopN-rebase
stupid mistake
Merge remote-tracking branch 'origin/druid-0.7.x-fastTopN-rebase' into druid-0.7.x-fastTopN-rebase
Aggressive unrolling in PooledTopNAlgorithm
unroll multi-value dimensions
Aggressive dimValue unrolling in PooledTopNAlgorithm