Adds a column to the remote servers activity page for a 7 day
count of forwarded mobile push notifications from
RemoteInstallationCount for each server, which will be `None`
if there is no data for the remote server with that ID.
Refactors get_page helper function so that the updates to the
query data for each row is done in the function that processes
the request.
Adds columns to the remote installation page for both the support
and analytics links.
Adds `analytics/views/remote_activity.py` to the files without
100% backend test coverage.