Partially resolves Next Game link

Does not support skipping games or configuring sort order.
Improved unit-testability

Made Game.goToNextPendingGame unit-testable (eschewed $.post() and added
Env.window as a mock for window), wrote a test for it, improved the
tests for Game.pageAddGameNavigationFooter, and changed the backend code
to return a proper $data object.
Multiple fixes to how I was performing unit tests

Also slight refactoring to make testing easier.
Fixing jshint and checkstyle issues
$&#*ing trailing whitespace
More trailing whitespace?!?
Switched to apiParsePost(), moved link to Login header

Switched to using an API method that calls apiParsePost(), moved the
"Next game" link to the Login header, added a message if you try to go
to the "Next game" from Overview when there is no next game, and updated
a bunch of relevant tests to match the new implementation.
Trying to make jenkins happy
jenkins
Conforming to coding standards
Updated tests to be consistent with refactored code
Merge pull request #736 from AdmiralJota/253_go_to_next_game

Added a link to go to the next game