add docker-credential-pass to dev img and use it in travis

Former-commit-id: 3deff7d6b345fd6c1e9bac71b446730631e891c9 [formerly 2525a27cb90b003f72c7d936e2f0224848e3e49f] [formerly c699da2816b0c61bfdaf0a8b40612b9d50734d73 [formerly 5ab5c7c24305b426b26778c92b17e711a269779e]]
Former-commit-id: 7ed9366f3c83f50afef6b40d0006c32256d053f7 [formerly 0fc1beb902fbadc6f6388b10b7ed319e15fcb7d4]
Former-commit-id: 7bd6bacacb114d72808ded8c102f8f14de450625

.travis.yml

@@ -6,14 +6,15 @@ addons:
   apt:
     packages:
     - docker-ce
+    - pass
 env:
   global:
   - USE_DOCKER="true"
   - WDIR=/go/src/github.com/filebrowser/filebrowser
 stages:
-- lint
-- test
-- release
+  - lint
+  - test
+  - release
 cache:
   directories:
     - vendor
@@ -30,7 +31,7 @@ jobs:
       script:
       - cp dockerfiles/filebrowser Dockerfile
       - docker build -t filebrowser/filebrowser .
-      - echo "$DOCKER_PASS" | docker login -u "$DOCKER_USER" --password-stdin
+      - ./build/docker_login.sh
       - docker push filebrowser/filebrowser
       - docker logout
       on:
@@ -40,7 +41,7 @@ jobs:
   - stage: release
     script:
       - cp dockerfiles/filebrowser Dockerfile
-      - echo "$DOCKER_PASS" | docker login -u "$DOCKER_USER" --password-stdin
+      - ./build/docker_login.sh
       - docker run --rm -itv $(pwd):$WDIR -v /var/run/docker.sock:/var/run/docker.sock filebrowser/dev goreleaser
       - docker logout
     if: tag IS present