increase assignment upload title from 10px to 12px

Refs: CNVS-26581

test plan:
- as a user with the old and/or new ui
- if you already have turned in an assignment that required a file
  upload... navigate to the course assignment and click the
  "submission details" link from the right-hand side bar
- if you do not have any assignment submissions as a file upload
  as a teacher edit one of your assignments to a file upload
  for the submission type
- then as the student - submit that assignment and then view the
  submission details from the right

- example from new ui: http://screencast.com/t/kPCaBjenS

Change-Id: I04b46ce126ddd6b1794ab963c9ce52ff4e851864
Reviewed-on: https://gerrit.instructure.com/73296
Tested-by: Jenkins
Reviewed-by: Colleen Palmer <colleen@instructure.com>
Product-Review: Colleen Palmer <colleen@instructure.com>
QA-Review: Myller de Araujo <myller@instructure.com>

app/stylesheets/components/deprecated/_fancy_links.scss

@@ -278,7 +278,7 @@ a.admin {
 @mixin attachment_link {
   background-repeat: no-repeat;
   background-position: left center;
-  @include fontSize(10px);
+  @include fontSize(12px);
   padding: 1px 0 2px 20px;
 }