fix yahoo/mojito-cli-jslint#6 exclusions too loose

new: allow for the no-type, no-mojito-exclusions case
new: exclusions match fwd or back slashes for windows

- change from config.json to config.js to use real regexes
- anchor regexes to avoid sub-string matching.
    i.e. so "docs" doesn't exclude "docs.js"
- allow for either fwd or back slashes (untested win compat)
- move patterns from `always` into relevant app/mojit/mojito
  sections. this enables usage without a type to be more general.
  users can supply own --exclude params if they do not
  specify type "app", "mojit", or "mojito".