provision after restart

This pull request is aiming to address the following.

1. After Jenkins restart, scheduler is not started.
2. Hence, if there were pending builds in the queue, they are never provisioned.
3. User can start new builds without first going to again save the plugin info.

When the provision method is called after restart for builds, the actual member field values saved by the plugin earlier have already been set to the field members and defaults for the not modifiable.

I also never found the DescriptorImpl::configure() method to be called. Based on what I read here,
https://wiki.jenkins-ci.org/display/JENKINS/Basic+guide+to+Jelly+usage+in+Jenkins
if @DataBoundCtr is defined then configure not required. But I did not remove it.