add outcome drawer icons

test plan:
go to stylguide (http://localhost:3000/styleguide#icons)
and verify that .icon-arrow-open-right and .icon-arrow-open-left
icons are visible and that classes are correct

Change-Id: Iac2eb10c179d86e28ea2c5d453d769a95ade7ccc
Reviewed-on: https://gerrit.instructure.com/29865
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Matt Fairbourn <mfairbourn@instructure.com>
Reviewed-by: Braden Anderson <banderson@instructure.com>
Product-Review: Patrick Cox <rpatrickcox@gmail.com>

app/stylesheets/utilities/_icons.scss

@@ -243,6 +243,10 @@ Either use `<a>` with icon desired icon class added or insert `<i>` inside `<but
   <span class="span3"><i class="icon-drag-handle"></i> icon-drag-handle</span>
   <span class="span3"><i class="icon-remove-from-collection"></i> icon-remove-from-collection</span>
 </div>
+<div class="row-fluid">
+  <span class="span3"><i class="icon-arrow-open-right"></i> icon-arrow-open-right</span>
+  <span class="span3"><i class="icon-arrow-open-left"></i> icon-arrow-open-left</span>
+</div>
 */
 
 // add icon font
@@ -484,6 +488,8 @@ h1, h2, h3, h4, .h1, .h2, .h3, .h4, p {
 .icon-reply-all-2:before { content: "\e104" }
 .icon-drag-handle:before { content: "\e105" }
 .icon-remove-from-collection:before { content: "\e106" }
+.icon-arrow-open-right:before { content: "\e107" }
+.icon-arrow-open-left:before { content: "\e108" }
 
 // deprecated in favor of .screenreader-only, which is meant to be usable anywhere
 span.screen-reader-text {