V4 interface changes

[keithdoggett]

Change the interface to match coord sys changes in RGeo 3.

[keithdoggett]

@BuonOmo that was part of the srs_database module which we removed from the core gem. It was basically the proj extension of that module. But since we are removing it from the core gem we have to remove it from here too since it references classes that were defined in that module.

[keithdoggett]

Thanks @BuonOmo!