LESS: button gradient mixin

LESS: button-gradient.less

.button-gradient (@start, @end) {
	background: -webkit-gradient( linear, left top, left bottom, color-stop(0.05, @start), color-stop(1, @end) );
	background: -webkit-linear-gradient(top, @start 5%, @end 100% );
	background: -moz-linear-gradient(top, @start 5%, @end 100% );
	background: -o-linear-gradient(top, @start 5%, @end 100% );
	background: -ms-linear-gradient(top, @start 5%, @end 100% );
	background: linear-gradient(top, @start 5%, @end 100% );
	background-color: @start;
	filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='@{start}', endColorstr='@{end}');
}