Add different stages for different events. (#67)

* add different stages for different events.

* Simplify the image build parameters for build stage.

* add master branch as condition for full stage.

.travis.yml

@@ -17,7 +17,14 @@ env:
 
 jobs:
   include:
-    - stage: rake full
+    - stage: build
+      if: type = pull_request
+      install: true
+      script:
+      - docker build --build-arg BUILD_TERRAFORM_VERSION=${TERRAFORM_VERSION} -t ${IMAGE_NAME} .
+      - docker run ${IMAGE_NAME} rake build
+    - stage: full
+      if: type = push AND branch = master
       install: true
       script:
       - docker build --build-arg BUILD_TERRAFORM_VERSION=${TERRAFORM_VERSION} --build-arg BUILD_ARM_SUBSCRIPTION_ID=$ARM_SUBSCRIPTION_ID --build-arg BUILD_ARM_CLIENT_ID=$ARM_CLIENT_ID --build-arg BUILD_ARM_CLIENT_SECRET=$ARM_CLIENT_SECRET --build-arg BUILD_ARM_TENANT_ID=$ARM_TENANT_ID -t ${IMAGE_NAME} .