Reorder tests to run in ascending order of speed.

Cucumber and jshint tests are slow, jasmine is fast, so run the fast ones first, and we'll get failures quicker.
Removed forceExit flag from jasmine_node task

Allows other tasks to run after that one.
Merge pull request #282 from alphagov/enhancement/test-reorder

Reorder tests to run in ascending order of speed.