In order to produce a consistent build across the board, we must hardcode
several package versions. We must additionally specify compatible
versions for any sub-dependency that we have a requirement upon.
In this instance, the only sub-dependency which has an effect upon the
overall output is grunt-contrib-uglify's dependency upon uglify-js.
Since change in uglify-js may lead to changes in the generated output, we
must specify a fixed version of that dependency. That version must be
compatible with the dependency signature for grunt-contrib-uglify or the
dependency manager will just download a different version.
This issue also bumps the version of uglify-js to a version which changes
the output. This is the latest version at time of commit.
