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Fail gracefully on Travis if Thrift connection is unstable

Now that it's only a couple of tests of legacy schema behavior, we don't have
to fail the CI build just because Thrift is acting up. These tests will still
fail when running locally.
Specify Rubinius platform-specific gems in a way Appraisal can handle
Show full backtrace for Rake test suite failures

Also don't fail fast when running from Rake (e.g. on Travis)
Merge pull request #65 from outoftime/cql-rb

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