Add copyFromSafe to ValueVectors.  Correct directionality of variable length copyFrom.
DRILL-185: Extend code/clean code generator and add first aggregate functions.
DRILL-178 Creating JSON Storage engine
DRILL-190 (part1) First pass at join operator (includes work from JN).
DRILL-190 (part2)
 - MergeJoinBatch handles record batches
 - JoinStatus tracks state across input and output batches
 - MergeJoinBatchBuilder builds a selection vector of right-side batches which may be rescanned
 - implement code stubs for merge join
 - add field expression parsing and start of generated merge join code
 - code generator support for merge-join's copyLeft(), copyRight(), compare() and compareNextLeftKey()
 - add line prefixes to generated code log
 - support VectorContainers in declareVectorValueSetupAndMember()
 - fix vector allocation in MergeJoinBatch
 - fix missing values from left batch when right batch has been exhausted
 - fix nullable handling in generated merge join code.  make simple merge join test use multiple batches.
 - fixes for sv4 batch support, additional multi batch test
DRILL-190 (part3) Fixes for integration between JSON changes, updated CodeGenerator and merge join
DRILL-121 RPM and DEB packages
DRILL-187 move hadoop dependency to top level pom
DRILL-188 add profiles to build with hadoop artifacts from vendors: mapr, cloudera, hortonworks