Re-implement this module as a pure JS wrapper around node-gdal

[springmeyer]

We should be able to drop the C++ code here, depend on node-gdal, and clean up the js code so that all tests still pass.

/cc @GretaCB @brandonreavis.

[brandonreavis]

This should be mostly done in this branch: https://github.com/naturalatlas/node-srs/tree/gdal-refactor.

The JS version of the C++ _parse method is here.

node-gdal was missing the SpatialReference.validate() / .fromESRI() methods, so I added those in. Once we publish the next version I'll start making sure all of the tests pass!

[springmeyer]

fantastic! I'll take a look later this week. One comment now though: I prefer spaces over tabs :)

[springmeyer]

Moving over at #59. Keeping the diff to a minimum for now to help review changes.

[springmeyer]

Done in #59