Update README file for blast_datatypes
Go back to downloading NCBI BLAST+ binaries.

Currently compilation on the Test Galaxy Tool Shed is failing
due to a BOOST change, so revert to fetching binaries.

This reverts commit 62079cf851aaf7142778ae490bcf12a9457c5ac2.
Try using new url_template with download_by_url
Update README file... hope this works on overnight test