Upgrade to ember 1.9

Hey I was using growl in an ember 1.9 project. After I installed it my project startup time was suddently VERY long. I thought it could be because of competing handlebars versions (2 sets of compilers? Or maybe just way to many files..). I may be completely wrong with the theory, but in practice when I forked growl and upgraded it to ember 1.9 my projects startup time  came back to normal. 

I had to remove one test in the process as it didn't work. And it seems that it didn't work because the function you used (`_classStringForProperty`) has changed in the meantime. Or I may have broken the test with the upgrade, it would be nice if you could look at it and see what's wrong.

Anyway I think it may benefit other people (as I think most of us upgrade ember more or less to the latest version) hence the pull request.