ModelService - getModel should support regular expressions

[rsoika]

the method getModel from the ModelService should also support regular expressions. This is needed to support the model change in a Workflow Result like this:

<model>     
     <version>(^rechnungseingang-[a-z]{2,3}-\d+(?:\.\d+)?$)</version>
     <task>5000</task>
     <event>990</event>
</model>