Merge pull request #17 from patrickarlt/master

Allow converting and parsing null island
Merge pull request #18 from patrickarlt/master

verison 1.0.2
Merge pull request #19 from patrickarlt/master

Strip invalid rings out of polygons on conversion
v1.0.3
Merge branch 'master' of github.com:Esri/terraformer-arcgis-parser
fix #20
fix #21