chore(doc-gen): add a jquery deploy environment, and give examples one index per environment

Adds a jQuery environment, and updates dgeni-packages dependency to add a processor
to the docs.angularjs.org package which runs after example index files have been generated.
This processor copies the index file once for each deployment environment, adding custom
shared scripts described in that env.

This does not yet handle changing the target of the iframe, so those all point
to the default no matter the version of docs being accessed.