#537 - show dialog on new version

.../deadlocker8/budgetmaster/controller/AboutController.java

...n/java/de/deadlocker8/budgetmaster/settings/Settings.java

...de/deadlocker8/budgetmaster/settings/SettingsService.java

...getmaster/utils/eventlistener/UpdateInstalledVersion.java

src/main/resources/static/js/about.js

src/main/resources/static/js/main.js

src/main/resources/templates/about.ftl

src/main/resources/templates/helpers/navbar.ftl

src/main/resources/templates/settings/settings.ftl

src/main/resources/templates/whatsNewModal.ftl