Restore ogrext includes and cimports

Fix for Toblerity#523

Rename config environment marker

Resolves Toblerity#665

Do not include gdal.pxi

Check against odd compound CRS

Update __init__.py

Revert to old tar tests for 1.8

Don't clobber credentials of the outer environment

Require GDAL 2 for crs_wkt test

Merge branch 'master' of github.com:Toblerity/Fiona