Recompile Stylus files as needed on development mode
Require LiveScript 1.2
Modularize the Gruntfile and make it user-overridable
Change dbapi-root's default config to match DBAPI's
Replace explicit UglifyJS task with optimization by RequireJS
Rename Grunt build targets

Now, `dev` means “development mode”, `release` actually means
“release testing mode” and `deploy` means “actual release mode”.

For dbapi-root, `development` means `dev` and `release`, and
`production` corresponds to `deploy`.