Organize Gruntfile

- split up config into several files
minor: edit demo-rc task description
Install grunt-replace npm package
minor: fix YUIDoc for private Map prop
Use grunt-text-replace instead of grunt-replace

- grunt-replace is actually templating
  string prefixed with '@@'
compiled changed to docs

(fixed cdn paths)
More Gruntfile organization

- was able to use 'grunt-text-replace- instead
  of custom tasks for demo-rc and version.
- Refactored demo and staging deployment,
  to make a lot more sense
  (and, I'm not totally sure it was really working before...()