MAPG-69 implement sign up functionality

views/signup/activate.php

@@ -0,0 +1,9 @@
+<?php require ROOT . '/views/templates/main_header.php'; ?>
+<?php require ROOT . '/views/templates/header.php'; ?>
+<div class="main">
+    <h2>Account activation</h2>
+    <div class="box">
+        <p class="error justify">Activation failed. Please check the link you entered or retry <a href="/signup" title="Sign up">sign up</a>!</p>
+    </div>
+</div>
+<?php require ROOT . '/views/templates/main_footer.php'; ?>