Added request class

ref #2

src/models/WelcomeMail.ts

@@ -0,0 +1,16 @@
+import { IsEmail, IsNotEmpty, IsString } from 'class-validator';
+
+/**
+ * Simple welcome mail request class for validation and easier handling.
+ */
+export class WelcomeMail {
+
+    @IsString()
+    @IsEmail()
+    @IsNotEmpty()
+    address: string;
+
+    @IsString()
+    @IsNotEmpty()
+    selfserviceToken: string;
+}