fix(ticksTooltip): Fix the positioning bug on Firefox due to tooltip on flex element.

Fixed by adding the tooltip-append-to-body config element to enforce the tooltip to be added to the
body.

Discussed in #209

Author: Valentin Hervieu

src/rzSliderTpl.html

@@ -12,7 +12,8 @@
 <ul ng-show="showTicks" class="rz-ticks"> <!-- // 9 The ticks -->
   <li ng-repeat="t in ticks track by $index" class="tick"
       ng-class="{selected: t.selected}" ng-style="t.style"
-      ng-attr-uib-tooltip="{{ t.tooltip }}" ng-attr-tooltip-placement="{{t.tooltipPlacement}}">
+      ng-attr-uib-tooltip="{{ t.tooltip }}" ng-attr-tooltip-placement="{{t.tooltipPlacement}}"
+      ng-attr-tooltip-append-to-body="{{ t.tooltip ? true : undefined}}">
     <span ng-if="t.value != null" class="tick-value"
       ng-attr-uib-tooltip="{{ t.valueTooltip }}"
       ng-attr-tooltip-placement="{{t.valueTooltipPlacement}}">{{ t.value }}</span>