* #4678: Converting strings to Date when schema.type is Date within aggregate function
* Added test cases to test new date match aggregate query
* Added function to parse match aggregate arguments and convert necessary values to Date objects
* Added missing return value
* Improved code quality based on suggestions and figured out why tests were failing
* Added tests from @dplewis
* Supporting project aggregation as well as exists operator
* Excluding exists match for postgres
* Handling the $group operator similar to $match and $project
* Added more tests for better code coverage
* Excluding certain tests from being run on postgres
* Excluding one more test from postgres
* clean up
* Support for Aggregate Queries
* improve pg and coverage
* Mongo 3.4 aggregates and tests
* replace _id with objectId
* improve tests for objectId
* project with group query
* typo
