Added a mutation method to the helper. This is used to handle command arrays, which allows users to easily perform methods on values in the dataLayer.
Fixed a but in the command processing code and renaimed the function from mutateValue_ to processCommand_ to fit better with the current processUpdate_ method. Updated tests accordingly.
Added stronger error checking when executing user supplied functions. Added more tests.
Fixed a stupid comment formatting error.
Removed an extra space at the end of a line to make the linter happy.
Made the abstract model interface a member variable of the DataLayerHelper instead of a local variable. Updated tests to account for this.
Removed local instance of the abstractModelInterface.
Changed the structure of the DataLayerHelper which allowed me to clean up the tests and decouple them. Cleaned up the TODOs as well.
Made the abstract model interface builder a member of the helper instead of being internal to DataLayerHelper.
Merge pull request #3 from AlexRNau/master

Added support for Command Arrays and Custom Methods, which should allow users to easily modify data in the dataLayer.