Merge branch 'improve-mr-build-times' into 'master'

Change builds to only build the specific module

See merge request marcel.schwarz/2020ss-qbc-geofence-timetracking!87

.gitlab-ci.yml

@@ -8,6 +8,10 @@ build-vue:
     - docker build --pull -t vue .
   rules:
     - if: $CI_MERGE_REQUEST_ID
+      changes:
+        - frontend/**/*
+      when: always
+    - when: never
 
 build-backend:
   image: docker:latest
@@ -19,6 +23,11 @@ build-backend:
     - docker build --pull -t backend .
   rules:
     - if: $CI_MERGE_REQUEST_ID
+      changes:
+        - backend/**/*
+      when: always
+    - when: never
+    
 
 build-android:
   image: docker:latest
@@ -30,3 +39,7 @@ build-android:
     - docker build --pull -t android .
   rules:
     - if: $CI_MERGE_REQUEST_ID
+      changes:
+        - android/**/*
+      when: always
+    - when: never