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.
Oh, I see, sorry.

* pycrypto should be installed with --prefix=#{libexec}
* jrnl should be installed with --prefix=#{prefix}
* then, jrnl's executables will already be in prefix/bin and you don't need the bin.install line. The env_script_all_files invocation will then move the originals to prefix/libexec/bin and put scripts into bin that invoke the original executables (now in libexec/bin) with a PYTHONPATH that picks up pycrypto.