More flexible failover timeout configuration.
The following option should be added to report plugins failover as well as standard sensor failover:
- failover_initial_timeout -> Value of the initial timeout when failover start.
- failover_increase_method -> When an attempt to recover from failover fail, it will
increase the current failover timeout depending on it's value. Accepted value are
'+ y' and 'x y'. In the first case, y will be added to the current timeout value.
In the second case, the current timeout value will be multiplicated by y.