Fix travis script

Author: aensidhe

.travis.yml

@@ -20,8 +20,10 @@ before_script:
   - docker -v
   - docker-compose down
   - docker-compose up -d
-  - cd samples/docker-compose && docker-compose down
-  - cd samples/docker-compose && docker-compose up -d --build
+  - pushd samples/docker-compose
+  - docker-compose down
+  - docker-compose up -d --build
+  - popd
 
 script:
   - dotnet build -f netcoreapp1.0 src/tarantool.client