Automatic Workflow Construction improvements

Pending Activities:

1. Remove hardcoding of Extract from IntentLearner.java. Move the logic and handle classification via Rivescript which is more flexible.

2. Format should be flexible. Current format has a fixed pattern "Extract from FileName using Fox".

3. Support Multiple Extractors and target graphs. Current code supports default extractor and default target graph. Support Complex workflows.

4. Support more intuitive user conversations if user misses any parameter in his query.

Start with IntentLearner.java and review how Extract is currently hardcoded. Then examine the Rivescript-based classification boundary and map the requested flexible formats, multiple extractors and target graphs, and missing-parameter conversations into an implementation plan. Done means these four workflow improvements are supported without the current fixed assumptions.

Written by the indexing model from the issue text.