overwrite install steps

Author: lixingwang

.travis.yml

@@ -4,6 +4,10 @@ go:
 sudo: required
 services:
   - docker
+cache:
+  bundler: false
+  directories:
+  - .build-cache          # images.txt
 # Handle git submodules yourself
 git:
     submodules: false
@@ -14,6 +18,8 @@ jobs:
       # Do a github login using token
       before_install:
         - "echo -e \"machine github.com\n  login ${GITHUB_USER_TOKEN}\" >> ~/.netrc"
+      install:
+        - "echo \"Install process\""
       script:
         - touch flogo-contrib.tgz
         - tar cvfz flogo-contrib.tgz --exclude=flogo-contrib.tgz .