change login user input tooltip

closes #424

Author: lmenezes

app/views/auth/login.scala.html

@@ -39,7 +39,7 @@ <h4>Cerebro
           <form class="form-signin" action="auth/login" method="POST">
             <div class="form-group">
               <label for="inputUser" class="sr-only">User</label>
-              <input type="text" name="user" id="inputUser" class="form-control form-control-sm" placeholder="LDAP user" required autofocus>
+              <input type="text" name="user" id="inputUser" class="form-control form-control-sm" placeholder="User" required autofocus>
             </div>
             <div class="form-group">
               <label for="inputPassword" class="sr-only">Password</label>