Syntastic fix and prettying up output

Fixing the syntastic integration, as well as adding a newline to the output of expressions for disambiguation.

I think you may have been using an older version of syntastic. I don't see that method `syntastic#makeprg#build` anywhere. I'm going off of [scrooloose/syntastic](https://github.com/scrooloose/syntastic/blob/7c638f6f70ce2cbf96b87ccfc55ed558d49b144c/plugin/syntastic/makeprg_builder.vim) master.