Create mongodb_js_inject_collection_enum.rb

This module was tested against a small php application I wrote interfacing with MongoDB 2.2.7

https://gist.github.com/brandonprry/c2de8ac2be825007c4de
Update mongodb_js_inject_collection_enum.rb

This adds a bit more error handling, and better decision making in regards to false responses.
Update mongodb_js_inject_collection_enum.rb

No need to make extra requests. Off by one.
Update mongodb_js_inject_collection_enum.rb

Fix some logic bugs that caused incorrect results.
Update mongodb_js_inject_collection_enum.rb

some @jvennix-r7 fixes
Land #3430, @brandonprry's generic MongoDB injection enum.