improved ROR retrieve in doi2rdm

These release trims the https://ror.org/ prefix from the ROR retrieve in doi2rdm for funders (issue #50). The func lookupROR now takes a trimPrefix parameter. It also includes an additional Python script get_eprint_documents.py which will fetch the documents for an eprint id from a remote EPrints server via scp and place them in a simplified directory called "problem_files".