Add "retry fetch" button to collection show page

[lwrubel]

When the embargo changes or there was an error in the data provided for a collection, the user may want to re-run the previous fetch. In the case of a previous fetch job where no WARCs were downloaded, provide a "Retry fetches" button. The button should only be active in the case where most recent fetch had no WARCs downloaded / druid registered.

Button should:

• Delete the previous fetch_month.
• Use FetchJobCreator's run method on the collection. (This will fetch crawls up until but not including the current month.)

[justinlittman]

Only the previous fetch_month or all fetch_months up to the last successful?

[lwrubel]

Thanks, should be all fetch_months up to the last successful, respecting embargo.