Release Name: 0.1.3

Notes:
Now supports three different XML parsers (REXML, Libxml, and Expat) and new OSM API BBox call.


Changes:
* Added parser code for using REXML, Libxml, or Expat parser. REXML is now the default
* API call to relation history now available
* Negative IDs are now allowed on objects
* Added OSM::API.get_bbox method