Merge pull request #47 from OpenGeoscience/john/remove-cjson

John/remove cjson
Add minimal test for vtkOsmLayer

Also updated vtkMap constructor to initialize default StorageDirectory
Check for curl error, and remove image file on error
Merge pull request #48 from OpenGeoscience/john/updated-directory-logic

Update filesystem interface to specify root storage directory in vtkMap.
Merge branch 'master' into john/geojson-feature

Resolved conflicts in:
	Testing/CMakeLists.txt