Update: rename cert-functions.sh to simple-ca.sh. Fix badge link.

run-tests.sh

@@ -25,7 +25,7 @@
 set -e
 
 # Load the certificate functions
-source "$(dirname "$BASH_SOURCE[0]")/cert-functions.sh"
+source "$(dirname "$BASH_SOURCE[0]")/simple-ca.sh"
 
 function clean_up_test_dir() {
     if [[ -d "$CERT_DIR" ]]; then