add jshint to `make test`

* add a lint target to the Makefile that runs jshint
* fix all jshint errors from the default config
* have the make test target run the lint target
I believe JSHint is incorrect there, and I'd like to use a flag to tell it so.

Apparently, I'm in [good company](https://github.com/jshint/jshint/issues/13) with this belief.