Small changes to the aggregate documentation
Add first draft of new Java API "Debugging" section
Improved Debugging section in Java API documentation
Splitted examples and adapted to new Java API
Updated Java Quickstart to new Java API
Update CLI documentation
minor fixes in CLI documentation
Added documenation for data source and sinks in new Java API
Updated front page, removed MR/Hadoop from heading, reworked API section, added runtime engine section