Use docker-build on the master branch

Author: yetist

.travis.yml

@@ -6,7 +6,7 @@ services:
   - docker
 
 before_install:
-  - curl -Ls -o docker-build https://github.com/mate-desktop/mate-dev-scripts/raw/travis/travis/docker-build
+  - curl -Ls -o docker-build https://github.com/mate-desktop/mate-dev-scripts/raw/master/travis/docker-build
   - chmod +x docker-build
 
 install: