fix blueprint sidebar on files admin view

refs MC-178

test plan:
- navigate to the file page on a blueprint master course
- verify that blueprint sidebar can be opened by clicking

Change-Id: Ic1c961b891b0bb0c87cb278499b3c9feab372274
Reviewed-on: https://gerrit.instructure.com/110354
Tested-by: Jenkins
Reviewed-by: Ed Schiebel <eschiebel@instructure.com>
QA-Review: Heath Hales <hhales@instructure.com>
Product-Review: Felix Milea-Ciobanu <fmileaciobanu@instructure.com>

Author: Felix Milea-Ciobanu

app/stylesheets/bundles/blueprint_course_settings.scss

@@ -4,6 +4,7 @@
   position: fixed;
   top: 0;
   right: 0;
+  z-index: 10;
   padding: 10px 3px;
   border-bottom-left-radius: 5px;
   background-color: $ic-brand-primary;