Merge branch 'release-0.8' into develop
Removed comment cruft and added a couple
Ezid::TestHelper#ezid_test_mode! now uses `EZID_TEST_USER`, `EZID_TEST_PASSWORD`,
`EZID_TEST_HOST` and `EZID_TEST_SHOULDER` env vars if set.
Merge pull request #21 from duke-libraries/test-env-vars

Test environment variables
Added version info constants and class method to Client.
Merge pull request #22 from duke-libraries/version

Added version info constants and class method to Client.
Version 0.9.0
Merge branch 'release-0.9'