Convert MonitoredCassandraClusterExample to java
Deletes ApplicationBuilder.Builder

- Removes the Builder
- Adds ApplicationBuilder.newManagedApp(...) for use
  by tests.
Mark ApplicationBuilder as @Beta
Examples extend AbstractApplication instead of ApplicationBuilder
converting postConstruct to init
Merge pull request #635 from ahgittin/fix/ApplicationBuilder-as-beta

change postConstruct to init (per @aledsage with minor fixes)