Arbitrary number of actions, at least one ProcessChain.

We still enforce them to be in blocks, i.e. we cannot mix actions with processChains.
Add test for empty processChain.

Changed the warning message from "No processChain steps are defined for this processChain. Such processChains have no effect and should be omitted." to "No processChain steps are defined for this processChain. A processChain should have at least one step showing a view.".
Fix broken validator test due to new DSL structure.
Merge pull request #11 from ps-md2/feature/actions-process-chain-in-wfe

Each Workflow Element requires at least one Process Chain and accepts any number of actions
Merging branch "Feature/actions process chain in wfe"