Handle errors, read diffs from the DB, etc.

Lots of error handling, diff reading, and other bits to implement some
of the API server logic.
Cast JSON as text when we select it as text
Remove error call that needs proper logging
client-demo should dump listed conflicts
Unknown entity/source error messages
Make lint slightly happier
Formatting w/ upgraded haskell-src-exts
Add SomeInternalKey and a creation operation
First cut of "resolve conflict" operation

Needs some more error handling.
Correct handling of IN sql operator
Make lint slightly happier
Inspector Pingu and the Case of the Missing Case
Merge pull request #107 from anchor/wip-server-functionality

Make "list conflicts" work