using c++11 regex to construct url based on a urlTemplate per datasource. And extract tileID from url also uses regex. ...Much cleaner now.... Moved comments from cpp to the header
Merge branch 'tile-management' of https://github.com/tangram-map/tangram-es into tile-management
const arguments, CheckDataExists call to GetData
added calls to geometry extrusion
check for null json value
added implementation for geometry extrusion
fixed bug for base poly moved to top if min_height different than featureheight.
fixed comparison operator for tileID
fixed tests based on changes done to dataSource