Run nose in verbose mode so we can see the tests being run/skipped. Override __str__ in PillowTestCase for nicer output, and make sure all tests are derived from PillowTestCase.
Fail fast: -x to stop running tests after the first error or failure
Use unique class names to match filenames
Merge some similar tests to a single file
Merge pull request #810 from hugovk/verbose_failfast

Tests: Be verbose and fail fast