pbfgraphbuilder Fixes

Fix a bunch of issues with the pbf graphbuilder. Now creates a connected graph it seems.

@dgearhart @gknisely @kevinkreiser 
that guys is failing the build. also can we please move this stuff to the header directory and make it part of the library? i think it would be useful to have the bits that write tiles as part of a library so other applications could write tiles (maybe for updates or something else we haven't thought of)