[Frontend] Timeline Gantt bar mods to allow small min-width

open #965
- CSS adjusted to handle min-width of 2px and better
approach to ellipsizing text;
- Angular ng-class added to hide icon and title if
width less than a value;
- Rounded corners on bars removed;

platform/features/timeline/res/templates/activity-gantt.html

@@ -20,6 +20,7 @@
  at runtime from the About dialog for additional information.
 -->
 <div class="t-timeline-gantt l-timeline-gantt s-timeline-gantt"
+     ng-class="{ sm: gantt.width(timespan, parameters.scroll, parameters.toPixels) < 25 }"
      title="{{model.name}}"
      ng-controller="TimelineGanttController as gantt"
      ng-style="timespan ? {