Replace unicode check with new svg icon

A good bit of CSS was required to keep the text color changing along
with the text it is nestled within.

Also: took this opportunity to increase the contrast of the number and
verified section right under the contact name in the group members view.

FREEBIE

stylesheets/_index.scss

@@ -95,6 +95,9 @@
   background-color: $grey_l !important;
   color: $grey_d;
   border-color: rgba(0,0,0,0.05);
+  .verified-icon {
+    @include color-svg('/images/verified-check.svg', $grey_d);
+  }
 }
 
 .tool-bar {