MultiCASPipeline: pipeline working with CAS multipliers; use in YodaQAApp

Now, we need to figure out how to build aggregate engines, so
temporarily disable QuestionAnalysis (instead, we directly call
WordTokenizer).
uimaFit migration: Autoload types and indexes
uimaFit migration: Discard XML descriptors of all other pipeline stages too
MultiCASPipeline: Do not set typeSystem on aggregate AEs
QuestionAnalysis: Re-introduce Aggregate AE wrapping WordTokenizer