Added validation of number of guests

If number of guests is 255 (which is the default value), no email will be sent
to the recepient. Most normal users have Javascript enabled, so their browser
should throw an error if the number of guests isn't filled out.

src/main.rs

@@ -106,6 +106,15 @@ fn validate_email(email: &String) -> bool {
     Regex::new(r"^[a-zA-Z0-9\.\-_]+@[a-zA-Z0-9\-\.]+\.[a-zA-Z]+$").unwrap().is_match(email)
 }
 
+fn validate_guests(guests: &u8) -> bool {
+    // Check if the default number of guests (255) changed.
+    if guests < &255 {
+        true
+    } else {
+        false
+    }
+}
+
 fn strip_tld(url: &str) -> Option<String> {
     // Get the top level domain which is used to determine the language
 
@@ -204,7 +213,7 @@ fn submit_task (host: HostHeader,
         Some(x) => {
             // Check input for anything strange or something that does not look like
             // an email address.
-            if validate_name(&x.name) && validate_email(&x.email) {
+            if validate_name(&x.name) && validate_email(&x.email) && validate_guests(&x.guests){
                 // Create HashMap to use with strfnt
                 let mut vars = HashMap::new();
                 vars.insert("name".to_string(), &x.name);
@@ -255,7 +264,7 @@ fn submit_task (host: HostHeader,
                         &settings);
                 }
             } else {
-                result = Err("Validate e-mail or name went wrong.".to_string());
+                result = Err("Validate e-mail, name, or number of guests went wrong.".to_string());
             }
 
             // Send a message to the sender's e-mailaddres to inform about