Allow the use of the Google Closure compiler for minifying and optimizing generated javascript

[octopuscabbage]

Fixes issue #122

[octopuscabbage]

I didn't write any additional tests for this because none of the functions seemed particularly testable.

[octopuscabbage]

Forgot to add the dependencies, but they are there now. Adds one additional dependency 'network-uri'

[octopuscabbage]

having a hell of a time satisfying the network uri dependency

[bergmark]

Thanks for the pull request,

Unfortunately there are a number of issues i see with this approach:

• Adding/modifying post-processing steps will require modifying rest-gen again
• Introduces new dependencies, HTTP and network. These are pretty dated packages by now. Network is hard to install for windows users and we already use better http-client dependencies for rest (http-client).
• Requires internet connectivity, doesn't allow to use a local version of closure

Extending what I wrote in #122 (comment) I'd rather we introduce a function generateJs :: JsConfig -> IO ByteString or similar, then you can easily use your approach without modifying rest-gen further.

[bergmark]

Actually, this is already possible by calling mkJsApi directly instead of using generate. But It would be nice to be able to use the predefined flags anyway, I started working on this on the gen-modular branch.

[octopuscabbage]

When are you planning to merge your gen modular branch? I could try moving some of the code over there and also adding in a command line compiler.

As for the dependencies, I can use http-client instead of HTTP I just thought you were already using network (because of yaml file for jenkins)