Change RSS default importer to accomodate multiple values in <dc:creator>

I've added a source called 'authors'. It returns an array. If you want to format this as a comma-seperated string, use the Feeds Tamper plugin "Implode".

I tested code using DrupalPod extension, added new field text field "all authors" with unlimited values and another field with one value.
First field is imported correctly, second generates correct warning
" All authors one line (field_all_authors_one_line): All authors one line: this field cannot hold more than 1 values.
Please check your mappings. "
Marking RTBC

Tested on Pubmed Import, works as expected

Thanks for testing! I merged the code.