reverted travis file config files

Author: HugoMario

.travis.yml

@@ -45,8 +45,8 @@ before_install:
   # set python 3.6.3 as default
   - source ~/virtualenv/python3.6/bin/activate
   # to run petstore server locally via docker
-  - docker pull swaggerapi/petstore:unstable
-  - docker run -d -e SWAGGER_HOST=http://petstore.swagger.io -e SWAGGER_BASE_PATH=/v2 -p 80:8080 swaggerapi/petstore:unstable
+  - docker pull swaggerapi/petstore
+  - docker run -d -e SWAGGER_HOST=http://petstore.swagger.io -e SWAGGER_BASE_PATH=/v2 -p 80:8080 swaggerapi/petstore
   - docker ps -a
   # Add bats test framework and cURL for Bash script integration tests
   - sudo add-apt-repository ppa:duggan/bats --yes