UI and API improvements for working with large repositories

- Change the tag check bar to only select the current page (by default), but allow for selecting ALL tags
- Limit the number of tags compared in the visualization view to 10
- Fix the multiselect dropdown to limit itself to 10 items selected
- Remove saving the selected tags in the URL, as it is too slow and overloads the URLs in Chrome when there are 1000+ tags selected
- Change the images API to not return locations: By skipping the extra join and looping, it made the /images API call 10x faster (in hand tests)

Fixes #292
Fixes #293

static/directives/repo-view/repo-panel-changes.html

@@ -3,14 +3,14 @@
        error-message="'Could not load repository images'">
     <h3 class="tab-header">
       Visualize Tags:
-      <span class="multiselect-dropdown" items="tagNames" selected-items="selectedTags"
+      <span class="multiselect-dropdown" items="tagNames" selected-items="selectedTagsSlice"
             item-name="tag" item-checked="updateState()">
         <span class="tag-span">{{ item }}</span>
       </span>
     </h3>
 
     <!-- No Tags Selected -->
-    <div class="empty" ng-if="!selectedTags.length">
+    <div class="empty" ng-if="!selectedTagsSlice.length">
       <div class="empty-primary-msg">No tags selected to view</div>
       <div class="empty-secondary-msg">
         Please select one or more tags above.
@@ -18,7 +18,7 @@
     </div>
 
     <!-- Tags Selected -->
-    <div ng-show="selectedTags.length > 0">
+    <div ng-show="selectedTagsSlice.length > 0">
       <div id="image-history row" class="resource-view" resource="imagesResource"
            error-message="'Cannot load repository images'">