feat(plugin): ngHint plugin

Don't worry about testapp/ngHint/ngHint.js
That wouldn't work.  The new object would never be put into `ngHintLog[location]`, so any manipulation of `pageLog` would be lost when the function exists.  I could do this if I also added add `ngHintLog[location] = pageLog` later though, if you're prefer it being two lines instead of one.  Or I could just rearrange this line into `var pageLog = ngHintLog[location] || (ngHintLog[location] = {})` which might be clearer.