Remove uglify

hi @triblondon - I wonder whether this could be considered...

Reasoning:-

- The tool we're using for js compression is closure compiler rather than uglify so if we were to need this we ought to use the same tool.
- It makes it difficult to do development on components, which is the primary use case for obt [ especially as sourcemaps aren't supported right now ]
- If we put in a compression task it would be better if it was opt-out-able.