[SPARK-2854][SQL] Finalize _acceptable_types in pyspark.sql

This PR aims to finalize accepted data value types in Python RDDs provided to Python `applySchema`.

JIRA: https://issues.apache.org/jira/browse/SPARK-2854

Author: Yin Huai <huai@cse.ohio-state.edu>

Closes #1793 from yhuai/SPARK-2854 and squashes the following commits:

32f0708 [Yin Huai] LongType only accepts long values.
c2b23dd [Yin Huai] Do data type conversions based on the specified Spark SQL data type.