Fixes #21

Moves Mocha instance creation to after require option has been
processed to allow for use of custom Mocha UI's.
Adds tests for #21
Merge pull request #22 from itaylor/master

Fixes #21
version 0.6.1
trying to figure out what conditions cause grunt to exit early still
Fix for async failure after before that starts an HTTP server
Merge branch 'earlyExit' of https://github.com/pghalliday/grunt-mocha-test into earlyExit