feature: checkbox to exclude captive/unknown occurrences

[ekrimmel]

On arctos.database.museum it is easy to return search results where species should not be correlated with biogeography. Users can exclude these results by defining collecting_source but this field is relatively hidden. Suggestion to add a checkbox in the (top part?) of the Locality search tab which, when checked, would exclude results of specimens where collecting_source does not equal "wild caught."