Add tests to catch upcoming VARCHAR/DATETIME serialization changes

[roback]

Add test cases so we catch the upcoming changes in mysql-binlog-connector 1.0.

From shyiko/mysql-binlog-connector-java#131 (comment):

• DATETIME/DATETIME_V2/TIMESTAMP/TIMESTAMP_V2/DATE/TIME/TIME_V2 deserialization to longs (Unix timestamp).
  This is BACKWARD-INCOMPATIBLE change.
• BINARY/VARBINARY deserialization ("binary" data deserialization produces incorrect value unless default charset is ISO-8859-1 shyiko/mysql-binlog-connector-java#56).
  This is BACKWARD-INCOMPATIBLE change as CHAR/VARCHAR/BINARY/VARBINARY are now returned as byte[] (which you can obviously convert to String with new String(byte[], Charset) if needed).