Revert "Retry external link check if response code is 0"
Revert "Retry external link check if response code is 0"

This reverts commit 53a6407a5ac4d545e8f82920fec1426a7cdde589.

gjtorikian/html-proofer,gjtorikian/html-proofer,gjtorikian/html-proofer,gjtorikian/html-proofer,gjtorikian/html-proofer