Revert "Merge branch 'master' of https://github.com/kivy/kivy"

This reverts commit 1c6af52f47df6e8f4238a3c52681e4b39cd3cd92, reversing
changes made to ed8c62a13bc1077e2db31ee56fafe645dd0335b3.
Revert "User-override of default font through config to achieve smaller APK's"

This reverts commit ed8c62a13bc1077e2db31ee56fafe645dd0335b3.