event logs: provide download option for data provider

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Allow data providers to download their event logs (e.g.
http://data.gbif.org/dataset/provider/201/logs/) for further analysis and
tracking

A data provider suggested to also display the total number of errors at the
top of the list. In this case, the display and count should default to
include only the last indexing run, as otherwise numbers will continue to
go up instead of down (which is what the provider would like to see after
correcting issues).

Original issue reported on code.google.com by josecua...@gmail.com on 31 Jul 2009 at 1:34