Add Gitlab-CI for testing

.gitlab-ci.yml

-image: "rust:latest"
+image: "rust:alpine"
 
 services:
   - mysql:latest
 
+stages:
+  - build
+  - test
+
 variables:
   MYSQL_DATABASE: test
   MYSQL_ROOT_PASSWORD: test_database
   DATABASE_URL: mysql://root:$MYSQL_ROOT_PASSWORD@mysql/$MYSQL_DATABASE
 
 build:
+  stage: build
   script:
-    - apt-get install libzmq3-dev
+    - apk add zeromq
 
 test:cargo:
+  stage: test
   script:
     - rustc --version && cargo --version 
     - cargo test --all