Added commit path filtering.

By adding a filter to commit you can commit only certain features or featureTypes. This is useful if you have a lot of changes but want to split them into several commits.
Fixed issue with getDefaultGeometry

The getDefaultGeometry function was returning an Optional instead of a Geometry.
Added ConfigGet operation

Added header to configOp, which was missing it
Merge pull request #58 from volaya/configget

Added ConfigGet operation
Call ConfigGet instead of ConfigOp where useful and make the code more readable
Optimized commit path filtering so that it doesn't create multiple trees.

Revised the way path filtering is handled so that it supports multiple paths for filtering.
Merge remote-tracking branch 'kelseyishmael/commitPathFilter' into commitPathFilter
Commands are public API, so guard their internal state when setting mutable arguments.