fix(.travis.yml): declare env vars on one line

Without this, Travis CI expands the build matrix and sets
one environment variable per build, which was not intended.

Author: mboersma

.travis.yml

@@ -7,8 +7,7 @@ services:
   - docker
 env:
   # HACK(bacongobbler): make travis tests work
-  - DEIS_REGISTRY=travis-ci/
-  - DOCKER_BUILD_FLAGS="--pull --no-cache"
+  - DEIS_REGISTRY=travis-ci/ DOCKER_BUILD_FLAGS="--pull --no-cache"
 install:
   - make docker-build
 script: