Adds meetup_map_embedder

This JS uses the Google maps API to plot the event venue on a Google
map.
meetup_event_embedder plots the venue on a map
Corrects typo in retrieving the venue zip

venue zip is now set successfully in google maps URL
Removes deprecated iframe-embedding code.

The Google Maps iframe was abandoned in favor of using the Google Maps
API.
sigId and sig no longer options passed to meetup

These values now intended to be hard-coded in meetup#events