Convert data feature warning to use bootstrap alert

Also rearrange dialog to fit with standard sidebar layouts, so that
the close icon and load buttons are not within the paragraph.

There may be a better way to construct this!

app/assets/javascripts/index/browse.js

@@ -49,15 +49,20 @@ OSM.initializeBrowse = function (map) {
 
   function displayFeatureWarning(count, limit, add, cancel) {
     $("#browse_status").html(
-      $("<p class='warning'></p>")
-        .text(I18n.t("browse.start_rjs.feature_warning", { num_features: count, max_features: limit }))
-        .prepend(
-          $("<span class='icon close'></span>")
-            .click(cancel))
+      $("<div>")
         .append(
-          $("<input type='submit'>")
-            .val(I18n.t("browse.start_rjs.load_data"))
-            .click(add)));
+          $("<h2>")
+            .text(I18n.t("browse.start_rjs.load_data"))
+            .prepend($("<span class='icon close'></span>").click(cancel)))
+        .append(
+          $("<div class='inner12'>")
+            .append(
+              $("<p class='alert alert-warning clearfix'></p>")
+                .text(I18n.t("browse.start_rjs.feature_warning", { num_features: count, max_features: limit })))
+            .append(
+              $("<input type='submit'>")
+                .val(I18n.t("browse.start_rjs.load_data"))
+                .click(add))));
   }
 
   var dataLoader;

app/assets/stylesheets/common.scss

@@ -699,10 +699,6 @@ body.compact {
 }
 
 #browse_status {
-  p {
-    padding: $lineheight;
-  }
-
   input {
     display: block;
     margin-left: auto;