wrap by '.input-group-addon' support.

the html template like this:

	<div class="form-group">
		<div class="col-md-10 col-sm-10">
			<div class="input-group">
				<span class="input-group-addon input-group-addon-bootstrap-select">
					<select name="" id="" class="selectpicker ">
						<option value="" data-content=''></option>
					</select>
				</span>
				<input type="text" placeholder="" class="form-control" >
			</div>
		</div>
	</div>