added option to localize "Go top" button from pager; added option for custom pager -> data page selector

Example of usage: 

   GRID

this.$grid.bsGrid({
            $toolbar: this.$toolbar,
            uniqueName: 'usersGrid',
            pagerUrl: this.options.pagerUrl,
            pagerGoTopTitle: 'My Custom go top title',
            pagerDataPageContainer:'customPageSelector',
   .......


  PAGER

Or directly on bsPager 

$(element).bsPager({
       dataPageContainer: 'customPageSelector',
       goTopTitle: 'My Custom go top title'
...

   HTML 

Example of html for custom pager :
...
 <li><a data-customPageSelector="1" href="#">«</a></li>
 <li><a data-customPageSelector="2" href="#">«</a></li>
...