SSB DB2 2.7

I have just cut a new release of SSB DB2 after merging in support for box2 using ssb-db2-box2. This means we can now do private groups and encrypt bendy butt (meta feeds) messages. @mixmix has begun looking at what needs done in order to run ssb-tribes on top of db2 here. And I recently got it working in the browser as well. I took special care in db2 to make this as performant as possible by doing the minimum amount of work needed. This should scale pretty well even for a lot of groups.

This is a huge milestone!!! Amazing achievement @arj & @mixmix! Looking forward to testing this out and seeing #ahau use ssb-db2.