MAINTENANCE: Automated closing of pull requests.

This commit exists to close the following pull requests on Github:

Closes apache#706 (close requested by 'pwendell')
Closes apache#453 (close requested by 'pwendell')
Closes apache#557 (close requested by 'tdas')
Closes apache#495 (close requested by 'tdas')
Closes apache#1232 (close requested by 'pwendell')
Closes alteryx#82 (close requested by 'pwendell')
Closes apache#600 (close requested by 'pwendell')
Closes apache#473 (close requested by 'pwendell')
Closes apache#351 (close requested by 'pwendell')