Merge pull request #88 from salt-formulas/pr/preinstall-apt-https-tranpsort

preinstall apt https transport
diff --git a/.travis.yml b/.travis.yml
index 3cb3de2..577330b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,6 +2,11 @@
 services:
   - docker
 
+addons:
+  apt:
+    packages:
+    - apt-transport-https
+
 install:
   - pip install PyYAML
   - pip install virtualenv