bumped version number and relase date
bugfix: removed rogue debugging `raise` statement
bugfix: update registry with `until` when appropriate

When `--until` is specified, update the registry with this value,
instead of the time at which the harvest was initiated to avoid
missing records updated in the interim.
+func: Harvester return boolean for completion

The `harvest` method of `OAIHarvester` returns a boolean for whether
it completed harvesting the complete set of matching records. If
stopped (e.g. due to `--limit` option) then returns False.
bugfix: only update registry if harvest completed

Only update the lastHarvest timestamp in the registry if all
available records were harvested. Registry is not updated if it
stopped early (e.g. due to use of `--limit` option.)
removed some unused imports
registry listing made semantically more accurate

"last harvest" -> "last completed harvest"
bugfix: registry lastHarvest handling

- removed rogue debugging `raise` statement
- update registry with `--until` option when given
- only update registry if harvest completed
  (i.e. was not truncated with `--limit=N`)

Merge branch 'hotfix/1.1.1'