Disable suffix based matching for content negotiation

This was causing issues with aliases containing dots.

src/main/java/de/thm/arsnova/config/AppConfig.java

@@ -62,6 +62,7 @@ import org.springframework.scheduling.annotation.EnableScheduling;
 import org.springframework.web.servlet.config.annotation.ContentNegotiationConfigurer;
 import org.springframework.web.servlet.config.annotation.EnableWebMvc;
 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
+import org.springframework.web.servlet.config.annotation.PathMatchConfigurer;
 import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
 import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@@ -141,6 +142,11 @@ public class AppConfig implements WebMvcConfigurer {
 		configurer.defaultContentTypeStrategy(strategy);
 	}
 
+	@Override
+	public void configurePathMatch(final PathMatchConfigurer configurer) {
+		configurer.setUseSuffixPatternMatch(false);
+	}
+
 	@Override
 	public void configureViewResolvers(ViewResolverRegistry registry) {
 		registry.viewResolver(new InternalResourceViewResolver());