Test against newer versions

[nikosmichas]

Run tests against newer versions of Ruby and Rails

[coveralls]

Coverage remained the same at 46.038% when pulling 6ec5994 on nikosmichas:test_against_newer_versions into cc5fd43 on geokit:master.

[ryankopf]

This works for me. Testing procedure with git checkout master, git fetch origin pull/156/head:test_against_newer_versions, git merge master test_against_newer_versions, rake test.

Running:

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Finished in 0.456539s, 148.9466 runs/s, 297.8933 assertions/s.
68 runs, 136 assertions, 0 failures, 0 errors, 0 skips