Added jrnl formula

Hi there, 

I added a new formula for [jrnl](http://maebert.github.io/jrnl/) following your `contributing` guidelines.
It installs on a mavericks host and runs the test correctly.

If possible, please merge.

Thanks for your work.
I've changed this, but I also had to change the pythonpath variable to set it to this other one. But I got a warning I don't remember now and don't have in this host.

The good part is that the Dir call is not needed anymore.

Anyway I'll check that tomorrow and post back the information.