Override build_access_token so that expires_at can be parsed to an integer
build_access_token is protected, not private. Move access token retrieval into its own method
Move access_token request payload into another private method
Add basic test and clean up unnecessary Omniauth-OAuth2 overrides
Add specs
Specs for custom token retrieval
Merge pull request #2 from rzane/master

Make it work! - Nice work! Great job with the specs too. As far as refresh_tokens go, at least they've expanded on the documentation to potentially make this work!