Point quickstart scripts to 0.6.1-incubating
Change logging backend of SLF4j from Logback to Log4j for better compatibiltiy with YARN.
We'll still ship the Logback configuration file and pass them their path to the JVM so that
users can use Flink with Logback as well.

This closes #125
Change Partition Operator to actual general-purpose Operator

It is no longer a special-case operator that can only be used in front
of map-style operations.