Improve the task pause, play, and pass icons

I think these look better.

Change-Id: I0b8ee786c40914d155d185af455e6e6275fd0fc6

gr-task-plugin/gr-task-plugin.js

diff --git a/gr-task-plugin/gr-task-plugin.js b/gr-task-plugin/gr-task-plugin.js
index e49f493..d01acf7 100644
--- a/gr-task-plugin/gr-task-plugin.js
+++ b/gr-task-plugin/gr-task-plugin.js
@@ -107,7 +107,7 @@
           icon.tooltip = 'Failed';
           break;
         case 'READY':
-          icon.id = 'gr-icons:rebase';
+          icon.id = 'gr-icons:playArrow';
           icon.color = 'green';
           icon.tooltip = 'Ready';
           break;
@@ -117,12 +117,12 @@
           icon.tooltip = 'Invalid';
           break;
         case 'WAITING':
-          icon.id = 'gr-icons:side-by-side';
+          icon.id = 'gr-icons:pause';
           icon.color = 'red';
           icon.tooltip = 'Waiting';
           break;
         case 'PASS':
-          icon.id = 'gr-icons:check';
+          icon.id = 'gr-icons:check-circle';
           icon.color = 'green';
           icon.tooltip = 'Passed';
           break;