added networkdatasource abstraction to datasource and rearranged datasource/networkdatasource/mapzenvectortilejson functions based on the new networkdatasource abstraction
Merge remote-tracking branch 'origin/tileSourceAbstraction'
Merge branch 'master' into async-tiles;

Reorganized some of the new and renamed methods into the newly separated DataSource subclasses

Conflicts:
	core/src/dataSource/dataSource.cpp
	core/src/dataSource/dataSource.h
	core/src/tileManager/tileManager.cpp