include codemirror static files

[AlJohri]

I've seen other similar django widgets that package the static files with the codemirror app, default CODEMIRROR_PATH to use the pre-pacakged static files, and allow the user to override the setting.

Would you be interested in a PR that does something like this? It would make installing and using the package easier along with getting rid of a bunch of static files from my main repository. Thanks!

[lambdalisue]

If the license is ok, I would merge such PR thanks!