Fixed Grunt hook when not in development or production environments.

For those Sails apps that don't just use `development` and `production` (i.e.: also `test` or something similar), commit https://github.com/balderdashy/sails/commit/307ed1b2217f13eb7d61e18c0e3e333e4347f6a3 breaks Grunt by causing it to hang indefinitely. This PR fixes that.