Support data/joining based on relations

[adamfranco]

Current way-joining uses the name and ref tags on ways to identify ways that are part of the same 'road' and join them together in longer sequences for analysis.

It is possible (though cases have not been identified yet) that ways might not have ref tags themselves, but rather be members of relations that have name and/or ref tags that should apply to all member ways. As relations seem to be the way OSM data is heading, any code that looks at tags (in particular the joining code) should be improved to look at relations as well as tags on ways themselves.

• Identify example ways that are members of route relations, but do not name/reftags themselves as examples.
• Update joiner code in collector.py to identify and join ways based on relation membership.
• Update collector code to source names and other tags from relations if those are not equivalent to the same tags on the way itself.