confirmation mail now template based.

src/main/java/de/srsoftware/widerhall/web/TemplateServlet.java

@@ -1,6 +1,7 @@
 package de.srsoftware.widerhall.web;
 
 import de.srsoftware.widerhall.Configuration;
+import org.stringtemplate.v4.ST;
 import org.stringtemplate.v4.STGroup;
 import org.stringtemplate.v4.STRawGroupDir;
 
@@ -8,7 +9,6 @@ import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletResponse;
 import java.io.File;
 import java.io.IOException;
-import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.util.Map;
 
@@ -24,6 +24,10 @@ public abstract class TemplateServlet extends HttpServlet {
         loadTemplates();
     }
 
+    protected ST getTemplate(String name){
+        return templates.getInstanceOf(name);
+    }
+
     protected String loadFile(String filename, HttpServletResponse resp) {
         var path = String.join(File.separator,baseDir,"static",filename);
         var file = new File(path);