Added bijection-avro module. Updated bijection-guava to support various encodings

Added Avro Module which provides following injections
 
 * Binary Injection for both specific and generic avro records
 * Json injection for both specific and generic avro records
 * Binary injection using dataFileWriter which wraps avro schema with serialized bytes.

Updated bijection-avro to Guava 14.0. Added bijections for Base16, Base32, Base32HEX and Base64. I know there is already a Base64 bijection in Core but I would appreciate it if we leave the Gauva based Base64 bijection in bijection-gauva.

Let me know if you need me to change anything