GruntSetAppMode, SetAppModeConfig --> add function properties to prototype, don't replace entire prototype object
final result correctness check factored out in to Validators static module; end to end tests tidied up; SAME tests set to skip for now
_.each --> List.forEach (superfluous require removed)
SetAppModeExecutor - stub implementation
example-gruntfile - iterated example of how to use set_app_mode
Gruntfile.js - tidied up and removed redundant entries
GruntSetAppMode - updated ctor and grunt task registration to properly gather specified options (lots of cheeky adhoc testing here I didn't do in a TDD way)
Set end-to-end grunt test to skip permanently (need to work around grunt's async task queuing to test it); code format tweak in registration test
GruntSetAppMode - wrote code top down; SAME files validity tests can be pushed to new ModeGroupConfigCollection class, SAME is only responsible for applying known-valid plugin configurations
lib/grunt_set_app_mode.js - require path bug fix