Add custom writeUTF method to PythonRDD and make it replace DataOutputStream.writeUTF so that we can use items with greater size in pyspark. Also modify pyspark MUTF8Deserializer to expect the size of the data blocks to be represented by an integer instead of an unsigned short.
remove alignment
remove using MUTF to send data to pyspark and use UTF from getBytes instead.
Add test for writing large strings