added webpack-encore for managing frontend assets #113 (#122)

* updated installation docu #113
* rewritten login page #113
* added icheck plugin #113
* changed to YesNoType in edit forms #113
* updated CONTRIBUTING.md #113
* added start of developer docu #113
* added compile scripts and compiled assets #113

config/services_test.yaml

@@ -0,0 +1,9 @@
+services:
+    _defaults:
+        public: true
+
+    # If you need to access services in a test, create an alias
+    # and then fetch that alias from the container. As a convention,
+    # aliases are prefixed with test. For example:
+    #
+    # test.App\Service\MyService: '@App\Service\MyService'