CHOP-47. Part 3. Configurable behavior for missing fields.

Reviewed by: robert
CHOP-53. Makes ScriptRunner a subclass of Scalding's Tool class.

Reviewed by: kiyan
CHOP-37. Test serialization of column requests including filters.

Reviewed by: kiyan
CHOP-48. CHOP-49. Interact with avro/non-avro cell values.

Allow users to interact with avro and primitive cell values from a Kiji
table as Scala types in Chopsticks.
Handle conversions to Scala during table reads and conversions back to
Java during table writes.

Reviewed by: kiyan, robert
CHOP-69. KijiSlice is returned in tuples.
Incorporating R's changes after rebase.
Halfway through fixing tests
more work on tests
more test fixing