Merge branch 'feature/mongo_2.6.5_expressions_Let' of https://github.com/RiveraGroup/mungedb-aggregate into feature/mongo_2.6.5_expressions_Let
EAGLESIX-2695 Added a new test file. Populated it with some tests and some test stubs.
EAGLESIX-2695 Fixed some broken test cases.
Merge branch 'feature/mongo_2.6.5_expressions' into feature/mongo_2.6.5_expressions_Let
EAGLESIX-2695 bugfix. restored the check that ensures two arguments are passed in. Added rudimentary test cases.
EAGLESIX-2695 Added the check for the number of arguments. Added rudimentary tests.
Merge branch 'feature/mongo_2.6.5_expressions' into feature/mongo_2.6.5_expressions_Let
Merge branch 'bugfix/mongo_2.6.5_expressions_Let' into feature/mongo_2.6.5_expressions_Let

Conflicts:
	test/lib/pipeline/expressions/LetExpression_test.js
EAGLESIX-812 Intermediate GroupSource
Merge branch 'feature/mongo_2.6.5_expressions' into feature/mongo_2.6.5_expressions_Let
EAGLESIX-2695 Improving the tests, correct code bugs. More To Come
Merge branch 'feature/mongo_2.6.5_expressions' into feature/mongo_2.6.5_documentSource_Project
EAGLESIX-2695 More improvements, with More To Come.
EAGLESIX-2695 Corrected a bug in ObjectExpression that would cause optimizations to be dropped on the floor. Continuing to work through $let test cases.  More To Come.
EAGLESIX-3080: partial port of the test cases
Merge branch 'feature/mongo_2.6.5_expressions' into feature/mongo_2.6.5_documentSource_Group

* feature/mongo_2.6.5_expressions: (129 commits)
  EAGLESIX-2996 Updated test for LTMatchExpression
  EAGLESIX-2995 Updated test cases for LTEMatchExpression
  EAGLESIX-2997 Updated test cases for GTMatchExpression
  EAGLESIX-2651: Value: better sync w/ 2.6.5 changes
  EAGLESIX-2997 Got GTEMatchExpression working
  EAGLESIX-2651: AddToSet: use ValueSet, mv it out of expressions, refactor requires
  EAGLESIX-2651: ToUpper: better sync w/ 2.6.5 tests, minor formatting to code
  EAGLESIX-2651: ToLower: better sync w/ 2.6.5 tests, minor formatting to code
  EAGLESIX-2651: Concat: better sync w/ 2.6.5 code (mainly reordering and code formatting), reformat tests a little bit
  EAGLESIX-2651: Multiply: better sync w/ 2.6.5 code (mainly reordering), reformat tests a little bit
  EAGLESIX-2651: SetIntersection: better sync w/ 2.6.5 code and tests, add more methods to ValueSet for this
  EAGLESIX-2651: Value: minor fixes for consistency more than anything
  EAGLESIX-2651: SetUnion: add missing isAssociativeAndCommutative getter
  EAGLESIX-2651: SetUnion: better sync w/ 2.6.5 code and tests, use ValueSet
  EAGLESIX-2651: Set*: fix trivial issues
  EAGLESIX-2651: Set*: use ValueSet instead of Helpers
  EAGLESIX-2651: SetEquals: better sync w/ 2.6.5 code and tests; fix ManyArgsEqual test
  EAGLESIX-2651: SetDifference: better sync w/ 2.6.5 code and tests
  EAGLESIX-2651: SetDifference: mv test base to separate file
  EAGLESIX-2651: SetIsSubset: misc formatting for consistency
  ...
EAGLESIX-2695 Completed all test cases expect a full blown test that requires expressions that are not yet available.
EAGLESIX-812: Much of Group ported but not functional
EAGLESIX-2695 Fiddled with the test cases.
EAGLESIX-1695 in preparation for another merge with expressions