Better UX for managing teams

- Moves the add team member to an inline box, rather than a popup
- Feedback bar is now used to show when a member is added, invited or removed
- Fixes bugs around using the view on mobile

Fixes #1509

static/css/pages/team-view.css

@@ -1,5 +1,6 @@
 .team-view .co-main-content-panel {
   padding: 20px;
+  position: relative;
 }
 
 .team-view .team-title {
@@ -58,4 +59,10 @@
 
 .team-view .co-table-header-row:first-child td {
   padding-top: 10px !important;
+}
+
+.team-view .section-header {
+  text-align: left;
+  color: #aaa;
+  margin-bottom: 20px;
 }