🚑 fix travis global disable install

Fixes #101

Author: jayvdb

templates/travis.yml.jj2

@@ -32,7 +32,7 @@ stages:
 
 .disable_global: &disable_global
   before_install: false
-  install: true
+  install: false
   before_script: false
   after_success: false
   after_failure: false