AttributionDAO fails when provider mapping has institution but not collection code

[ansell]

When a provider mapping has an institution but not a collection code, the AttributionDAO is unable to find it as it presumes that the collection code will exist

biocache-store/src/main/scala/au/org/ala/biocache/caches/AttributionDAO.scala

Line 162 in cbabd9a

if(institutionCode!=null && collectionCode!=null){