Run javascript unit tests on build

[alechenninger]

This will require interfacing with node / npm from maven. There is an active project which can do this: https://github.com/eirslett/frontend-maven-plugin

It downloads node and npm so it seems pretty portable.

Related to this is to make sure unrelated bower_components code doesn't end up in final jar. This can probably be filtered out somehow with maven configs? (Exclude everything, then only include what we need?)

[alechenninger]

Running unit tests was implemented in #52

For minifying, opened #55

[alechenninger]

Woops, I thought that PR was merged, reopening this issue