Possibility to choose between choice types for lists

I provided a way to choose between types of choices, like single and multi select, radio buttons and check boxes. The changes were done based on the code of the "Exented Choice Parameter Plugin" (https://github.com/jenkinsci/extended-choice-parameter-plugin). So kudos to the creator(s) of this plugin for the code.

What I've changed:
* Added Chooser in the config of the Dynamic Choice Parameter and Scriptler parts
* The way the chosen parameters are checked against the valid choices
* The resulting array is converted to a comma separated String (don't know if there is another way how to do this but this works for me so far)
* Adapted the tests and translations

Since I've never done a pull request or "extensive" work like this on a Jenkins plugin (limited time) the code is not cream of the crop. So I might have overlooked something. Feel free to criticize (and/or reject the pull request). ;)

PS: Here is a screenshot:
![dynamic_choice_param_incl_types](https://f.cloud.github.com/assets/2979051/281447/fe216bbe-9177-11e2-9605-401c60a15d22.png)