solving little problems we had using the plugin and making quartz controller url configurable

We had some problems using this plugin. The url /jobs/configure is restricted to another application in our production environment, so we had to make a lot of workarounds to use this plugin in production. My modifications are a attempt to make the plugin a litte more configurable, so we can change the default behaviour more easily.

I just noted I have permission to push directly to this repo (I didn't know that!), should I simply push my modifications next time? :D