MAINTENANCE: Automated closing of pull requests.

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

Closes apache#3205 (close requested by 'srowen')
Closes apache#5478 (close requested by 'andrewor14')
Closes apache#4910 (close requested by 'srowen')
Closes apache#5080 (close requested by 'marmbrus')
Closes apache#537 (close requested by 'srowen')
Closes apache#5691 (close requested by 'srowen')
Closes apache#5469 (close requested by 'marmbrus')

Author: pwendell