Fixed bugs in ResourceEdit.pm.
Fixed bugs in ResourceEdit.pm.

 - In handling image data, 'identify' and 'convert' are now assumed to
   be in PATH instead of using hard-coded path names.
 - The 'image_data' field is now explicitly ignored when a record
   is added or updated, so that it doesn't generate an E_BAD_FIELD
   error.

paleobiodb/pbdb-new,paleobiodb/pbdb-new,paleobiodb/pbdb-new,paleobiodb/pbdb-new,paleobiodb/pbdb-new