Add case sensitivity support to Parquet Serde.

This is a small modification to ParquetHiveSerde to accommodate case sensitive fields through a serde property. 

An example use case in hive:
   CREATE EXTERNAL TABLE IF NOT EXISTS T(fieldName1 string, fieldname2 int, fieldNAME3 string)
   ROW FORMAT SERDE 'org.apache.hadoop.hive.ql.io.parquet.serde.SensitiveParquetHiveSerDe'
   WITH SERDEPROPERTIES ("casesensitive"="fieldName1,fieldname2,fieldNAME3)
   STORED AS INPUTFORMAT 'parquet.hive.DeprecatedParquetInputFormat'
   OUTPUTFORMAT 'parquet.hive.DeprecatedParquetOutputFormat'
   LOCATION '...';