make get_certificate more general

abra.sh

@@ -230,9 +230,13 @@ apply_blueprints
 
 get_certificate() {
 /manage.py shell -c """
-kimai = Provider.objects.filter(name='Kimai').first()
-saml = kimai.samlprovider
+provider_name='$1'
+if not provider_name:
+    print('no Provider Name given')
+    exit(1)
+provider = Provider.objects.filter(name=provider_name).first()
+saml = provider.samlprovider
 cert = saml.signing_kp
-print(cert.certificate_data) 
+print(''.join(cert.certificate_data.splitlines()[1:-1]))
 """ 2>&1 | quieten
 }