gitlab-ci updated

.gitlab-ci.yml

 ---
 image: mathiwr/amdis-base:debian9
 
+cache:
+  key: "$CI_BUILD_REF_NAME"
+  untracked: true
+  paths:
+  - install/
+
 stages:
   - build
   - demo
@@ -12,9 +18,6 @@ build:9-debug-gcc:
   stage: build
   script:
   - tools/build_amdis.sh --stage build --config Debug
-  artifacts:
-    paths:
-    - install/
   only:
   - master
 
@@ -22,9 +25,6 @@ build:9-release-gcc:
   stage: build
   script:
   - tools/build_amdis.sh --stage build --config Release
-  artifacts:
-    paths:
-    - install/
   only:
   - master
 
@@ -32,9 +32,6 @@ build:9-parallel-debug-gcc:
   stage: build
   script:
   - tools/build_amdis.sh --stage build --config Debug --parallel
-  artifacts:
-    paths:
-    - install/
   only:
   - master
 
@@ -42,9 +39,6 @@ build:9-parallel-release-gcc:
   stage: build
   script:
   - tools/build_amdis.sh --stage build --config Release --parallel
-  artifacts:
-    paths:
-    - install/
   only:
   - master