Add ability to clone previous events

Problem/Motivation

The Tampa Bay Drupal User Group has monthly meetings. It is difficult for us to update the community events page on a timely basis.

Proposed resolution

Enable previous events to be cloned.

Remaining tasks

1. Determine how cloning would work on drupal.org.
2. Add cloning to events.

User interface changes

Either a link or a button on an event to create a new event with the same data.