[SPARK-2314][SQL] Override collect and take in JavaSchemaRDD, forwarding to SchemaRDD implementations.

Author: Aaron Staple <aaron.staple@gmail.com>

Closes #1421 from staple/SPARK-2314 and squashes the following commits:

73e04dc [Aaron Staple] [SPARK-2314] Override collect and take in JavaSchemaRDD, forwarding to SchemaRDD implementations.

(cherry picked from commit 90ca532a0fd95dc85cff8c5722d371e8368b2687)
Signed-off-by: Reynold Xin <rxin@apache.org>