Bring back elementpath for tinyMCE, but hide in UI

Kenneth tools relies on this path being on the page in order for their stuff
to work. This brings back the html elementpath below tinymce, but hides it
using css from the UI so it isn't visible.

closes: CNVS-22759

Test Plan:
- Open up a view that had TinyMCE
- You should not see any html elementpath below the editor

Example with path: http://cl.ly/image/1O3u3J3j361w
Example without path: http://cl.ly/image/050n0Q1B1P2g

Change-Id: I93e7fa65c1d05a105c7e80e7b65ba4e4176fec4e
Reviewed-on: https://gerrit.instructure.com/61956
Reviewed-by: Mike Nomitch <mnomitch@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Stephen Jensen <sejensen@instructure.com>
Reviewed-by: Ryan Shaw <ryan@instructure.com>
Tested-by: Jenkins

app/stylesheets/bundles/tinymce.scss

@@ -3,3 +3,4 @@
 @import 'vendor/lightskin.scss';
 @import 'base/environment';
 @import 'our_custom_tiny_mce_stuff/tiny_like_ck_with_external_tools.scss';
+@import 'our_custom_tiny_mce_stuff/tiny_mce_ui_customizations.scss';

app/stylesheets/our_custom_tiny_mce_stuff/_tiny_mce_ui_customizations.scss

@@ -0,0 +1,5 @@
+// This allows the html stack below tinymce to remain
+// on the page, but hidden from view
+.mce-statusbar .mce-flow-layout {
+  visibility: hidden;
+}

public/javascripts/tinymce.config.js

@@ -65,7 +65,7 @@ define([], function(){
       remove_script_host: true,
       resize: true,
       block_formats: "Paragraph=p;Header 2=h2;Header 3=h3;Header 4=h4;Preformatted=pre",
-      elementpath: false,
+
 
       extended_valid_elements: "@[id|accesskey|class|dir|lang|style|tabindex|title|contenteditable|contextmenu|draggable|dropzone|hidden|spellcheck|translate|align|role|aria-labelledby|aria-atomic|aria-busy|aria-controls|aria-describedby|aria-disabled|aria-dropeffect|aria-flowto|aria-grabbed|aria-haspopup|aria-hidden|aria-invalid|aria-label|aria-labelledby|aria-live|aria-owns|aria-relevant|aria-autocomplete|aria-checked|aria-disabled|aria-expanded|aria-haspopup|aria-hidden|aria-invalid|aria-label|aria-level|aria-multiline|aria-multiselectable|aria-orientation|aria-pressed|aria-readonly|aria-required|aria-selected|aria-sort|aria-valuemax|aria-valuemin|aria-valuenow|aria-valuetext],iframe[src|width|height|name|align|style|class|sandbox|allowfullscreen|webkitallowfullscreen|mozallowfullscreen],i[iclass],a[hidden|href|target|rel|media|hreflang|type|charset|name|rev|shape|coords|download],div,span,#p,h2,h3,h4,h5,h6,header,ul,ol,li[value],ol[reversed|start|type|compact],pre[width],table[border|summary|width|frame|rules|cellspacing|cellpadding|bgcolor],tbody[char|charoff|valign],td[colspan|rowspan|headers|abbr|axis|scope|align|char|charoff|valign|nowrap|bgcolor|width|height],tfoot[char|charoff|valign],th[colspan|rowspan|headers|scope|abbr|axis|align|char|charoff|valign|nowrap|bgcolor|width|height],thead[char|charoff|valign],title,tr[char|charoff|valign|bgcolor],ul[compact]",