[new_frontend] Hardening JSHint and jscs

If you thought the syntax rules for checking in before were too easy... have fun!
Hopefully I got the goofy true/false parts right in JSHint. It's tricky when some `true` values seem to enable a feature and disable others. :shrug:

Also, deleted a few JSHint rules where a jscs equivalent was available, or we had the rules in both places (which is bad/sloppy on my part).

Also, unrelated, but I noticed this while doing a `$ grunt`:

> _**Running "useminPrepare:html" (useminPrepare) task**
> Going through app/index.html to update the config
> Looking for build script HTML comment blocks
> **Fatal error: require.js blocks are no more supported.**_

Not sure if that was there before, or byproduct of a recent tweak or bump in a package version, but I thought it was worth mentioning.