[GraphHopper] Public Transport Support

[Thomas Bürli]

Hi,

So, I implemented a very rudimentary public transport support for 
graphhopper.

It works with a time-expanded graph like it is described in 
http://d-nb.info/1001586921/34. I choose the time-expanded approach 
mostly because I didn't know how a time-depended graph should be 
implemented.
A unit test is added which show how the GTFSReader is used and how 
routing can be done.

You can take a look at it at 
https://github.com/initdch/graphhopper/tree/feature/GTFS . I would 
appreciate your feedback.

Regards,
Thomas