Added travis CI, updated rake tasks, and fixed an issue related to ruby 1.9.3

Hi @wimm,

I've done some hacking on rubyntlm. Would you mind perusing my commits, merging my pull request and setting up the travis hook?

I've made Travis run the tests on loads of ruby versions, and it passes on every one except jruby-1.8mode, where jruby itself falls over giving a java backtrace.

John