EAGLESIX-2700 reviewed code and test cases.
Merge branch 'feature/mongo_2.6.5_expressions' into feature/mongo_2.6.5_expressions_And
EAGLESIX-2700 Fixed errors in AndExpression. Tests are complete and pass.  However, I don't like the result of the optimization. It is missing obvious trivial optimizations.
EAGLESIX-2700 Added a method to allow the optimizer to work much better. Improved test cases.
Merge branch 'feature/mongo_2.6.5_expressions_And' into feature/mongo_2.6.5_expressions_ToLower
EAGLESIX-2722 Minor change to ToLowerExpression, filled out the tests a little.