Fixed wrong number of arguments (2 for 1) when running ts:index

Fixed this error:
```
wrong number of arguments (2 for 1)
/home/bitnami/.bundler/ruby/1.9.1/ts-delayed-delta-5462f126db4a/lib/thinking_sphinx/deltas/delayed_delta.rb:23:in `cancel_jobs'
/home/bitnami/.bundler/ruby/1.9.1/ts-delayed-delta-5462f126db4a/lib/thinking_sphinx/deltas/delayed_delta.rb:145:in `block in <top (required)>'
Tasks: TOP => ts:index
```
by changing request to Delayed::Job in cancel_job method a little bit