FastByteArray*Stream implementations to replace syncronized JDK ByteArray*Stream

In CASSANDRA-2820 I reintoduced the FastByteArrayInputStream and FastByteArrayOutputStream to cassandra. These steams are un-synchronized versions of the Apache Harmony ByteArrayInputStream and ByteArrayOutputStream respectively.

During my own testing of the streams I found a big difference in the performance of the standard JDK BA*S steams and the FBA*S streams on most JREs. Then cassandra load testing also showed an up to 10% improvement in cassandra performance using these streams.

Then Thrift has TByteArrayOutputStream which contains a way to get the underlying byte[] buffer without a deep copy that would probably be a good further enhancement.

Patch to follow.