Guard, PG, Bourbon, Q

Adding guard to auto-run specs, rewriting specs to use `let` and thus be **a lot** faster. The whole suite runs in 3 seconds now. Also added the ability to edit comments.
This is not safe, with this code you can actually update any comment on any board by tampering with `id` in input params. Please change to `@commit.comments.find(params[:id])`