Dropdown menu should support several lists inside

[marcoscv-work]

Dropdown Clay component needs to use different context lists in combination with the rest of elements which are not a list.

This is a markup example:

__

<div class="dropdown-menu">
	<form>
		<div class="dropdown-section">
			<div class="input-group input-group-sm">
				<div class="input-group-item">
					<input class="form-control input-group-inset input-group-inset-after" type="text">
					<span class="input-group-inset-item input-group-inset-item-after">
						<button class="btn btn-unstyled" type="button">
							S-Icon
						</button>
					</span>
				</div>
			</div>
		</div>

		<ul class="unnamed-class">
			<li class="unnamed-class">
				<ul class="unnamed-class">
					<li class="dropdown-subheader">SUBHEADER</li>

					<li class="unnamed-class">
						<a class="dropdown-item" href="#1">Actions</a>
					</li>

					<li class="dropdown-divider"></li>

					<li class="unnamed-class">
						<a class="dropdown-item" href="#1">Actions</a>
					</li>
				</ul>
			</li>

			<li class="dropdown-divider"></li>

			<li class="unnamed-class">
				<ul class="unnamed-class">
					<li class="dropdown-subheader">SUBHEADER</li>

					<li class="unnamed-class">
						<a class="dropdown-item" href="#1">Actions</a>
					</li>

					<li class="dropdown-divider"></li>

					<li class="unnamed-class">
						<a class="dropdown-item" href="#1">Actions</a>
					</li>
				</ul>
			</li>
		</ul>
	</form>
</div>

[carloslancha]

Related with #425. Fixed in same pr.

[carloslancha]

Label this as next release