fix(datepicker): change to min width cells

- Change to use `min-width` due to issue in Firefox

Closes #4000
Fixes #3941

Author: Adam Tentis

template/datepicker/day.html

@@ -14,7 +14,7 @@
     <tr ng-repeat="row in rows track by $index">
       <td ng-if="showWeeks" class="text-center h6"><em>{{ weekNumbers[$index] }}</em></td>
       <td ng-repeat="dt in row track by dt.date" class="text-center" role="gridcell" id="{{::dt.uid}}" ng-class="::dt.customClass">
-        <button type="button" style="width:100%;" class="btn btn-default btn-sm" ng-class="{'btn-info': dt.selected, active: isActive(dt)}" ng-click="select(dt.date)" ng-disabled="dt.disabled" tabindex="-1"><span ng-class="::{'text-muted': dt.secondary, 'text-info': dt.current}">{{::dt.label}}</span></button>
+        <button type="button" style="min-width:100%;" class="btn btn-default btn-sm" ng-class="{'btn-info': dt.selected, active: isActive(dt)}" ng-click="select(dt.date)" ng-disabled="dt.disabled" tabindex="-1"><span ng-class="::{'text-muted': dt.secondary, 'text-info': dt.current}">{{::dt.label}}</span></button>
       </td>
     </tr>
   </tbody>

template/datepicker/month.html

@@ -9,7 +9,7 @@
   <tbody>
     <tr ng-repeat="row in rows track by $index">
       <td ng-repeat="dt in row track by dt.date" class="text-center" role="gridcell" id="{{::dt.uid}}" ng-class="::dt.customClass">
-        <button type="button" style="width:100%;" class="btn btn-default" ng-class="{'btn-info': dt.selected, active: isActive(dt)}" ng-click="select(dt.date)" ng-disabled="dt.disabled" tabindex="-1"><span ng-class="::{'text-info': dt.current}">{{::dt.label}}</span></button>
+        <button type="button" style="min-width:100%;" class="btn btn-default" ng-class="{'btn-info': dt.selected, active: isActive(dt)}" ng-click="select(dt.date)" ng-disabled="dt.disabled" tabindex="-1"><span ng-class="::{'text-info': dt.current}">{{::dt.label}}</span></button>
       </td>
     </tr>
   </tbody>

template/datepicker/year.html

@@ -9,7 +9,7 @@
   <tbody>
     <tr ng-repeat="row in rows track by $index">
       <td ng-repeat="dt in row track by dt.date" class="text-center" role="gridcell" id="{{::dt.uid}}">
-        <button type="button" style="width:100%;" class="btn btn-default" ng-class="{'btn-info': dt.selected, active: isActive(dt)}" ng-click="select(dt.date)" ng-disabled="dt.disabled" tabindex="-1"><span ng-class="::{'text-info': dt.current}">{{::dt.label}}</span></button>
+        <button type="button" style="min-width:100%;" class="btn btn-default" ng-class="{'btn-info': dt.selected, active: isActive(dt)}" ng-click="select(dt.date)" ng-disabled="dt.disabled" tabindex="-1"><span ng-class="::{'text-info': dt.current}">{{::dt.label}}</span></button>
       </td>
     </tr>
   </tbody>