Add lease_opts to the global option list

Without this patch, the cleaning_time option from lease_opts is missing
from the generated blazar.conf.

Change-Id: I21c1b2e1356c92725d099ef9d9ba3f9588e290b0

blazar/opts.py

@@ -35,6 +35,7 @@ def list_opts():
              blazar.cmd.api.opts,
              blazar.config.api_opts,
              blazar.config.cli_opts,
+             blazar.config.lease_opts,
              blazar.config.os_opts,
              blazar.db.base.db_driver_opts,
              blazar.db.migration.cli.command_opts,