Dependencies: Conditional & Simplified.

[timbohiatt]

1. Currently AirFlow assumes that all dependencies must be completed and "ALL_SUCCESSFUL" before the next task can run. However in Control-M XML Logic there are scenarios where Dependencies are conditional. For example where One OR Another task is has finished then start the next task.

2. Currently the Dependency tree is built but it is not optimized. We should explore the option of building a more dynamic dependency tree. This Should also assist with Readability.