Revert "Revert "Hub::Exception should inherit from StandardError""
Revert "Revert "Hub::Exception should inherit from StandardError""

This reverts commit a1e6d4ccc8fb60c7b812c821b61efaab07ee80fc.

travis-ci/travis-hub,travis-ci/travis-hub,final-ci/travis-hub,final-ci/travis-hub