Add getStreetEdges to Graph; Add functionality to Thrift API

1) Adds a getStreetEdges to the Graph object. Test it.
2) Adds a StreetEdge.canTraverse(TraverseModeSet) so that StreetEdges can be filtered by which traverse modes can traverse them (without constructing a RoutingRequest).
3) Adds some unit tests to PlainStreetEdge.
4) Format some files.
5) Add functionality to GetEdges() method on Thrift API to allow filtering of edges by which traversal modes can traverse them.

As usual, unit tests pass and everything builds.
Avi