Revert "Refuse to build if there's no CODE_SIGN_IDENTITY"

This reverts commit 4e09e0bbaaa498cc42091cdf836fd34259815626.
Revert "There, this should invert the swipe direction. I can't test it as I don't have a magic mouse. I'm sure milky will let me know."

This reverts commit 3013236bb640ead225b7e23d71f9440243667250