Add setupTask to update context

Hadoop reuses commiter when jvm is reused for multiple mappers.
Context provided to constructor may be updated during the committer's
lifetime.
Print success message on exit

To more easily validate success we grep logs for a known success
message.

Also printing task completion status as we encountered an issue where
tasks were being killed after error instead of failing.  The reason was
unclear, but this makes it easier to identify.
Fix partitioner per topic

Need to save partitioner instance per topic.
New arraylist is always empty.
Extract writing offset files to hooks

We also write the offsets to a plain text file that can be read without
hadoop to validate successful camus runs.
Add recordPartitions extention point

This allows additional behavior such as updating hive metadata once new
files have been moved into their final destination