Add a retry-attempts option.

The default number of maximum retry attempts is **3**. That number can be overridden by the extra data of the command.
Now, if you want to set a retry attempt for a specific queue, you can override both the default parameter and the extra data by setting the `retry-attempts` option with an integer number.

    --retry-attempts=2
You're entirely right; my bad :( I fix that: https://github.com/swarrot/SwarrotBundle/pull/31