#419 - add upload inputs to modal + load available image async from server

...a/de/deadlocker8/budgetmaster/images/MediaController.java

...main/java/de/deadlocker8/budgetmaster/utils/Mappings.java

src/main/resources/languages/base_de.properties

src/main/resources/languages/base_en.properties

src/main/resources/static/css/accounts.css

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

src/main/resources/templates/accounts/accountFunctions.ftl

src/main/resources/templates/accounts/availableImages.ftl

src/main/resources/templates/accounts/newAccount.ftl