Fixes to allow batching

* If a model run has never been done, calculate final weightings for all occurrences, else exclude those that do not yet have an environmental suitability (this happens during disease group setup)
* Don't run the model if there are no occurrences to send to it (can only happen if Minimum Data Volume = 0)
* Deployment scripts: override modelwrapper.rootUrl in common-override.properties
It doesn't, but it's in common.properties so I figured it could be overridden with the correct URL anyway...