www/rubygem-uglifier: Update from 3.0.0 to 3.0.2

3.0.2

• add top-level keep_fnames option that implies both compressor and mangler keep_fnames
• update UglifyJS to 2.7.3

3.0.1

• update UglifyJS to 2.7.0
• split JS dependencies to separate files

Approved by: swills (mentor)