fix(facepile): update button to include button attribute
fix(facepile): update button to include button attribute

Adds `type="button"` to `<button>` elements.

 Closes #390.

andikrueger/ng-officeuifabric,andikrueger/ng-officeuifabric,jjczopek/ng-officeuifabric,jjczopek/ng-officeuifabric,andrewconnell/ng-officeuifabric,jjczopek/ng-officeuifabric,andrewconnell/ng-officeuifabric,s-KaiNet/ng-officeuifabric,andikrueger/ng-officeuifabric,jjczopek/ng-officeuifabric,s-KaiNet/ng-officeuifabric,andrewconnell/ng-officeuifabric,s-KaiNet/ng-officeuifabric,ngOfficeUIFabric/ng-officeuifabric,andrewconnell/ng-officeuifabric,andrewconnell/ng-officeuifabric,ngOfficeUIFabric/ng-officeuifabric,andikrueger/ng-officeuifabric,ngOfficeUIFabric/ng-officeuifabric,s-KaiNet/ng-officeuifabric,s-KaiNet/ng-officeuifabric,jjczopek/ng-officeuifabric,ngOfficeUIFabric/ng-officeuifabric,andikrueger/ng-officeuifabric,ngOfficeUIFabric/ng-officeuifabric