Add options to control delay between script restarts.

This pull request along with changes to [forever-monitor](https://github.com/nodejitsu/forever-monitor/pull/15) provides options to add a delay between restarting a script.

This implements the feature request in issue [#350](https://github.com/nodejitsu/forever/issues/350).
The user can set a delay in milliseconds and increase it by using a configurable algorithm.
See the PR for forever-monitor for more details on these algorithms.