Add a method to remove badges from Jenkins builds

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Fix color logic for the Jenkins build badges

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Re-instate the border color #C0C000 for Jenkins build badges

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>