added classes to floor and ceil label to allow styling (#337)

src/rzSliderTpl.html

@@ -5,8 +5,8 @@
 </span> <!-- // 1 Highlight between two handles -->
 <span class="rz-pointer rz-pointer-min" ng-style=minPointerStyle></span> <!-- // 2 Left slider handle -->
 <span class="rz-pointer rz-pointer-max" ng-style=maxPointerStyle></span> <!-- // 3 Right slider handle -->
-<span class="rz-bubble rz-limit"></span> <!-- // 4 Floor label -->
-<span class="rz-bubble rz-limit"></span> <!-- // 5 Ceiling label -->
+<span class="rz-bubble rz-limit rz-floor"></span> <!-- // 4 Floor label -->
+<span class="rz-bubble rz-limit rz-ceil"></span> <!-- // 5 Ceiling label -->
 <span class="rz-bubble"></span> <!-- // 6 Label above left slider handle -->
 <span class="rz-bubble"></span> <!-- // 7 Label above right slider handle -->
 <span class="rz-bubble"></span> <!-- // 8 Range label when the slider handles are close ex. 15 - 17 -->