Organize effort to clear 2016 extension review queue

The 12/22/16 extension working group meeting concluded that pairing an extension review effort with the completion of the documentation would be a good way to road-test the doc and to show progress to the community. We thought we should start with extensions submitted in 2016 because there would be less bang for our buck in reviewing older extensions (due to an increased likelihood of abandoned extensions, extensions no longer compatible with a supported release, etc.).

Additional observations from Frank J. Gómez:

• 35 extensions were submitted for review in 2016, a 400% increase from 2015!
• There are 16 members of the extensions working group, according to the JIRA user group.
• In Allen's experience, 4 or 5 extension reviews per day is a good pace for someone getting started reviewing extensions.
• We should be able to get the 2016 backlog resolved in one day, even without full participation.
• Completing the relevant documentation by end of Jan 2016 seems reasonable.

Observations coalescing into a plan:

• During the month of January we get commitments from existing working group members and/or recruit new ones to take on some extensions.
• Authors of the extensions in the queue will be asked to create a JIRA review request ticket to ensure they are at least minimally engaged in the process. This will weed out abandoned extensions, we hope.
• During the first week or two of February, we cash in those commitments. At least two virtual sprints are organized (because we're spread across many timezones) so that reviewers can benefit from chatting with others doing the same work.