Add an error message to the mobile login page

This adds an error message to the mobile version of the login page
for failed logins, as requested in #3048

This (along with the standard login page) appears to use the Devise
i18n for the error message, which may need to be updated to reflect
the fact that we're not using email addresses for authentication.

app/views/sessions/new.mobile.haml

@@ -3,6 +3,8 @@
 -#   the COPYRIGHT file.
 
 #main_stream.stream
+  - flash.each do |name, msg|
+    %p{:class => "login_#{name}"}= msg
   #login_form
     .login-container
       = form_for(resource, :as => resource_name, :url => session_path(resource_name), :html => {:class => 'form-horizontal'}) do |f|

public/stylesheets/sass/mobile.scss

@@ -105,6 +105,15 @@ body {
     top: 1px solid #ccc; };
 }
 
+.login_error,
+.login_alert {
+  color: rgb(208, 49, 43);
+  text-shadow: 1px 1px 20px rgb(208, 49, 43); }
+
+.login_notice {
+  color: rgb(10, 150, 10);
+  text-shadow: 1px 1px 20px rgb(126, 240, 77); }
+
 #login_form {
   padding: 0;