Condtionally load Keen IO and don't fail if it's not loaded
travis-yml-stats: pass some more information to Keen IO

- event_type so we can track pull requests vs regular pushes
- matrix size so we can see how many jobs repositories test against
- owner_id/owner_type/owner so we can do a unique count on owners,
  similar to how we can do that for repositories

The reason for owner_id, owner_type and owner all being sent is
partially due to our database schema and partially due to the querying
API of Keen IO. First of all, we need both owner_id and owner_type since
the ID sequences of users and organizations are different, so the id
alone is not a guarantee of uniqueness. Second, we cant group by more
than one parameter, so we need the array/tuple form for grouping, but
the "normalized" version for querying directly on the values (useful for
looking at other values for organizations versus users).
Revert "do not automatically load keen publisher"

This reverts commit beaa1c74ff078f2820c65a3d6c4a2aa0bd6c9c0b.

As of b319f04cc8d0e647ed47f256b28a41ef995edcda Keen IO is now
"conditionally" loaded (we won't fail if it isn't there), so this isn't
needed anymore.