Bug fixes and improved error handling:

* Fixes intermittent "table does not exist" errors due to timed out
  connections.
* Fixes a failure where batch loads would fail if an old_ table from a
  previous run already exists.
* Raise an error if user tries to load an unknown table.
* Raise an error if user tries to refresh recent a table without an entry in
  the meta_last_sync_times table.
* Promote some warnings to failures.
* Bump version number.