Server side caching techniques shouldn't be disallowed. See: 3f42d3a#commitcomment-5084830
Also fix up a whole bunch-ton of other gemfile deps that had gotten awry.
This is in response to CVE-2013-0269. See https://groups.google.com/forum/?fromgroups=#!topic/rubyonrails-security/4_YvCpLzL58 for details.
I couldn't get the test suite to run at *all* with test-spec. Given that it hasn't seen a release since 2009, I doubt it's up for being adapted to modern test-unit conventions. I chose to switch to minitest purely because it is the standard in modern Ruby releases.
This will prevent us to overwrite the Content-Language header if the application sets it properly.