Cleaning up the Gruntfile into the grunttasks dir
Update the CONFIG_ROOT to handle the change in directory of the selectconfig task.
Merge pull request #550 from mozilla/grunt-refac

Grunt refactor

And thanks to [@vladikoff's suggestion](https://github.com/mozilla/fxa-content-server/pull/550#discussion_r9800061), our logs are down to 4700 lines!

r+ - thanks @pdehaan!