Enlarge the maximum number of hits for remote BLAST results

Currently, the max hits limit is 1000 in the remote BLAST dialog and 500 in the workflow element.
This value needs to be enlarged. For now, set this value to 5000.
Note that, as soon as annotations are completely moved to dbi, this value can be set to any integer value, see, for example, http://www.ncbi.nlm.nih.gov/staff/tao/URLAPI/new/node37.html.