align version variables in Dockerfile and frontend src code

mc_frontend/Dockerfile

@@ -23,4 +23,4 @@ COPY ./config.xml ./www/config.xml
 # workaround to fix the missing binding issue for node-sass
 RUN npm rebuild node-sass
 # initialize the version file, it will get updated later
-RUN echo "export const version = '';" | tee src/version.ts
+RUN echo "export const VERSION = '';" | tee src/version.ts

mc_frontend/package.json

 {
   "name": "mc_frontend",
-  "version": "2.7.7",
+  "version": "2.7.8",
   "author": "Ionic Framework",
   "homepage": "https://ionicframework.com/",
   "scripts": {