SQL example code for Python, as shown on [SQL Programming Guide](https://spark.apache.org/docs/1.0.2/sql-programming-guide.html)

Author: jyotiska <jyotiska123@gmail.com>

Closes #2521 from jyotiska/sql_example and squashes the following commits:

1471dcb [jyotiska] added imports for sql
b25e436 [jyotiska] pep 8 compliance
43fd10a [jyotiska] lines broken to maintain 80 char limit
b4fdf4e [jyotiska] removed blank lines
83d5ab7 [jyotiska] added inferschema and applyschema to the demo
306667e [jyotiska] replaced blank line with end line
c90502a [jyotiska] fixed new line
4939a70 [jyotiska] added new line at end for python style
0b46148 [jyotiska] fixed appname for python sql example
8f67b5b [jyotiska] added python sql example