Updates Indexing Issues (#34)

* Makes gdal an optional dependency

* Refactors all bae I/O into a single namespace.

* typos

* Fixes the gdal dependency test

* Adds tests for the JSON

* Tests fail without test data

* Updates for comments from @thareUSGS

* Adds ISIS3 V2 ControlNetwork Reader

* Adds hcube mixin object

* Updates to support tif M3, and fixes indexing issues