Make clear forms option configurable

We had an issue with unexpected behaviours when submitting forms with buttons with a 'name'. In some cases this name was not submitted with the form. 

Setting 'debug' to true would make this problem go away, this made it look like a timing issue.

Disabling the form clear variables setTimeout fixed the issue for us and the name is now submitted consistently. We do not re-use the form anyway so for us this flag solves the problem. 

Maybe a good configuration option to have by default, hereby the pull request containing this feature.