Revert "Add cli arg to rm the bw file link"

This reverts commit 199c9274.
We decided that this option is not needed when the header include
statistics about the percentage of relays that failed.

sbws/core/generate.py

@@ -61,9 +61,6 @@ def gen_parser(sub):
                         "other.")
     p.add_argument('-n', '--min-num', default=NUM_MIN_RESULTS, type=int,
                    help="Mininum number of a results to consider them.")
-    p.add_argument('-l', '--rm-link', action='store_true',
-                   help='If specified, remove latest.v3bw link when there '
-                        'are no relays to include in it.')
 
 
 def main(args, conf):