Fixed relative path issues in PWA setup

package.json

@@ -5,6 +5,7 @@
     "ng": "ng",
     "start": "ng serve",
     "build": "ng build",
+    "build-prod": "ng build --configuration production --base-href=/svg-path-editor/",
     "test": "ng test",
     "lint": "ng lint"
   },

update-gh-pages.sh

@@ -5,7 +5,7 @@ set -e
 git clone "https://github.com/Yqnn/svg-path-editor.git" .svg-path-editor-master
 cd .svg-path-editor-master
 npm install
-npm run build -- --configuration production
+npm run build-prod
 git checkout gh-pages
 rm -rf *.ico *.html *.js *.css *.txt assets
 mv dist/svg-path-editor/* .