This commit fixes all 1533 PHPCS errors that PHPCBF can fix automatically in the tests/ directory. Before this change there was a total of 3106 PHPCS errors in the WooCommerce repository and now there is 1573 errors.
This commit adds the composer package jdgrimes/wp-http-testcase directly to this repository instead of via composer. Doing this because I couldn't find a way to make this package work on Travis build jobs running older versions of PHP and I don't think it is worth investing much time on it.