#275 - implemented version check

pom.xml

src/main/java/de/deadlocker8/budgetmaster/Main.java

...adlocker8/budgetmaster/controller/SettingsController.java

.../de/deadlocker8/budgetmaster/services/HelpersService.java

...ocker8/budgetmaster/update/BudgetMasterUpdateService.java

...deadlocker8/budgetmaster/update/UpdateAvailableEvent.java

src/main/resources/application.properties

src/main/resources/repositories.json

src/main/resources/templates/settings.ftl