node-gyp changes

As per https://github.com/paixaop/node-sodium/issues/9#issuecomment-38010349 

1. Submodule approach abandoned and now takes the leveldb library approach using deps
2. Build moved over to node-gyp
3. Docker Node Test integration https://github.com/rvagg/dnt
4. Start of the move to tap test framework
5. Travis integration and initial pass

You will need to login to http://travis-ci,org with your github handle and enable your node-sodium repo.
After a subsequent commit the build status should just work.