Run tests against all mime-types version with appraisal rake or rake appraisal
The 'local_development' group is a way to specify gems you may use while developing the gem, but aren't required to run the tests.
Conditionals in a gemspec are only executed when building the gem. That is, when you run gem install, you get the built gem. If the gem was built under CRuby 1.9.3, it would not specify jruby-openssl or tlsmail as dependencies, no matter what platform or version of Ruby you are running gem install on. It only really makes sense to have them in the Gemfile for use in development.
…in specs Closes #300
…ut very explicit, I like explicit