Update bootstrap-timepicker.js

Changes to the file cover the following:
* creating optional arguments for the icon to use for the up and down arrows in the modal (left the default of 'glyphicon glyphicon-chevron-up' and 'glyphicon glyphicon-chevron-down', but using bootstrap 3 we were passing 'icon-chevron-up' and 'icon-chevron-down'.
* created a new optional parameter of "containerClass" (default is "bootstrap-timepicker", which matches the existing example markup), which allows to either using the existing example mockup, or create more modularized markup and have the js support it.

As an example, consider the following:

<div class="form-group multi-field" id="endTime-block">
	<div class="form-control-container-time input-append bootstrap-timepicker">
		<input id="endTime" type="text" class="form-control" data-minute-step="1" /></span>
	</div><!-- close .form-control-input-group-btn -->
	<div class="form-control-input-group-btn">
		<button class="btn btn-secondary add-on" type="button" id="endTimeBtn"><i class="icon-time"></i> <span>GMT</span></button>
	</div><!-- close .form-control-input-group-btn -->
</div><!-- close .multi-field -->

<script type="text/javascript">
	$('#endTime').timepicker({upArrowStyle:'icon-chevron-up',downArrowStyle:'icon-chevron-down',containerClass:'.form-group'});
</script>