added unit tests and fixed issue with stream refence hanging around
better seperation of concerns with backoff stratedgy and immortal stream
Add mocha test, handle tcp timeout, refactor immortal-stream

For tcp timeout support using horixon ntwitter fork until changes pulled upstream. Refactored ntwitter for readability and to fix state bug if immortal-stream is cycling often. closes #5. closes #4. The commit also meets some of the needs mentioned in https://github.com/AvianFlu/ntwitter/issues/20#issuecomment-4793546