Merge pull request #7 from Infactum/feature/ci-fix

CentOS build fix

appveyor.yml

@@ -35,7 +35,7 @@ install:
 build_script: 
   - sh: >- 
       mkdir build;
-      docker run --rm -v "$(pwd)":/src "$docker_image" /bin/bash -c "
+      docker run --rm -v "$(pwd)":/src "$docker_image":"$docker_tag" /bin/bash -c "
         mkdir build && cd build;
         export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig && cmake -DCMAKE_BUILD_TYPE=Release /src
         cmake --build .;