Updated to match nodemon 1.0 release

Fixes #28 

In order to support all of nodemon 1.0, we need support for [options.env](https://github.com/ChrisWren/grunt-nodemon#env) and execMap via the requirable nodemon interface. I don't think execMap is critical, and would be willing to push a new version without it, but it would be nice to match the whole api. @remy are you willing to add support for specifying process.env variables to nodemon?

Also, any thoughts on what the default logging should be? Currently it logs nodemon output without any color:
![screen shot 2014-01-11 at 13 48 49](https://f.cloud.github.com/assets/2061937/1894983/3800b250-7b0a-11e3-91b2-a96a4b36b6b2.png)