EXP-222. Improve generic Avro APIs.

issue: https://jira.kiji.org/browse/EXP-222

Add pack/unpack functions to KijiPipe for Specific and Generic records

fix reading and writing to counter columns

fix reading and writing to raw bytes columns

Write avro values to Kiji

Types are encoded to avro generic equivalent if possible

add Schema serialization; not actually working

make ColumnRequestOutput serializable

reading working for primitive types

remove AvroValues types

Added Kryo serializers for avro.

add SchemaSpec trait to specify how to read or write data

fix KijiJobSuite test

fix some more tests and serialization issues

ColumnRequest implementations need not be serializable

style fixes

KijiLocker to serialize non-Serializable objects

review: https://review.kiji.org/r/1317