Use <label>s rather than placeholders

isso/js/app/text/postbox.jade

@@ -5,13 +5,19 @@ div(class='isso-postbox')
                 = i18n('postbox-text')
         section(class='auth-section')
             p(class='input-wrapper')
-                input(type='text' name='author' placeholder=i18n('postbox-author')
+                label(for='isso-postbox__author')
+                    = i18n('postbox-author')
+                input(type='text' id='isso-postbox__author' name='author'
                       value=author !== null ? '#{author}' : '')
             p(class='input-wrapper')
-                input(type='email' name='email' placeholder=i18n('postbox-email')
+                label(for='isso-postbox__email')
+                    = i18n('postbox-email')
+                input(type='email' id='isso-postbox__email' name='email'
                       value=email != null ? '#{email}' : '')
             p(class='input-wrapper')
-                input(type='text' name='website' placeholder=i18n('postbox-website')
+                label(for='isso-postbox__website')
+                    = i18n('postbox-website')
+                input(type='text' id='isso-postbox__website' name='website'
                       value=website != null ? '#{website}' : '')
             p(class='post-action')
                 input(type='submit' value=i18n('postbox-submit'))