Add a .travis.yml file.
Fix the Gemfile's RUBY_VERSION check.
Check the RUBY_ENGINE when determining dependencies.
Skip the EmHttp handler tests on MRI 1.8.7.

The tests fail on MRI 1.8.7 due to the "method" method & to_proc bug:
http://stackoverflow.com/questions/4721708/is-this-a-bug-in-methodto-proc-ruby-1-8-7
Merge pull request #14 from halorgium/travis

Travis-CI all the Rubies