UglifyOps.singleFileWithSourceMapInAndOut is broken in 3.0.0+

[spencerhakim]

Attempting to use sbt-uglify with UglifyOps.singleFileWithSourceMapInAndOut results in ERROR: invalid option --in-source-map errors and the build failing. This CLI argument was removed in uglify-js v3, and the equivalent CLI argument is documented here.