pull the dockers first

Signed-off-by: Arnav Gupta <arnav@codingblocks.com>

Author: championswimmer

.travis.yml

@@ -10,6 +10,8 @@ before_install:
 
 install:
   - npm install -D
+  - docker pull codingblocks/judge-worker-c
+  - docker pull codingblocks/judge-worker-cpp
 
 script:
   - npm run test