Sets default srs

Avoids fatal error when shapefiles doesn't have a spatial reference system.
Avoids fatal error on invalid geometries

wraps the getGeometry() function in a try / catch block. If the geometry if invalid of can't be parsed, it continues with the next one instead of aborting the whole process.
Merge pull request #8 from amenadiel/master

Avoids fatal errors on null SRS and invalid geometry