[SPARK-4228][SQL] SchemaRDD to JSON

Here's a simple fix for SchemaRDD to JSON.

Author: Dan McClary <dan.mcclary@gmail.com>

Closes #3213 from dwmclary/SPARK-4228 and squashes the following commits:

d714e1d [Dan McClary] fixed PEP 8 error
cac2879 [Dan McClary] move pyspark comment and doctest to correct location
f9471d3 [Dan McClary] added pyspark doc and doctest
6598cee [Dan McClary] adding complex type queries
1a5fd30 [Dan McClary] removing SPARK-4228 from SQLQuerySuite
4a651f0 [Dan McClary] cleaned PEP and Scala style failures.  Moved tests to JsonSuite
47ceff6 [Dan McClary] cleaned up scala style issues
2ee1e70 [Dan McClary] moved rowToJSON to JsonRDD
4387dd5 [Dan McClary] Added UserDefinedType, cleaned up case formatting
8f7bfb6 [Dan McClary] Map type added to SchemaRDD.toJSON
1b11980 [Dan McClary] Map and UserDefinedTypes partially done
11d2016 [Dan McClary] formatting and unicode deserialization default fixed
6af72d1 [Dan McClary] deleted extaneous comment
4d11c0c [Dan McClary] JsonFactory rewrite of toJSON for SchemaRDD
149dafd [Dan McClary] wrapped scala toJSON in sql.py
5e5eb1b [Dan McClary] switched to Jackson for JSON processing
6c94a54 [Dan McClary] added toJSON to pyspark SchemaRDD
aaeba58 [Dan McClary] added toJSON to pyspark SchemaRDD
1d171aa [Dan McClary] upated missing brace on if statement
319e3ba [Dan McClary] updated to upstream master with merged SPARK-4228
424f130 [Dan McClary] tests pass, ready for pull and PR
626a5b1 [Dan McClary] added toJSON to SchemaRDD
f7d166a [Dan McClary] added toJSON method
5d34e37 [Dan McClary] merge resolved
d6d19e9 [Dan McClary] pr example