Revert "Adding grunt-cli to devDependencies."

This reverts commit 066dfb0754f9a4ecaee73756747679ef3b218be4.
Revert "Define Grunt locally, and use grunt-cli to build."

This reverts commit 003e6d8f4d42b9606fe2d0b88702f169811974e0.
Define an empty root by default.