fixing compiled file and tests

Hey there,

The compiled file was missing the variables in messageformat.include.js that you see below. Without them, pluralization messages were broken. I basically just lifted the implementation that [the main project uses to correctly format the files](https://github.com/SlexAxton/messageformat.js/blob/v0.1.8/bin/messageformat.js#L133-L166).

I also fixed the tests and updated them to test the case of a plural message format string.