Add Option To Renew License Before It Expires

Currently, there is no support for an option to renew the license before it expires.

The expiration date is not available to this module, but there can at least be a checkbox to optionally renew the license before it expires.

Other modules such as the Commerce License should be able to check this setting and take appropriate actions.

This patch only adds a checkbox input to allow other modules to implement license extensions for rolling intervals.

I created another patch for the Commerce License module to implement this which I will be submitting shortly for review.