Just test a subset of drivers
Add test coverage check
Ignore coverage and tox stuff
Add tox configuration
Add tests for closed file reads, seeks, and json to geom
Fix driver lookup handling for non-unique file extensions

Some drivers share identical file extensions so add the capability to filter
those which support writes and enforce checks on copy/create.
Improve test coverage
Add writeable key name as class attr
Kick off builds with 2.7