Fixes #1240 - Dropdown Menu added .dropdown-item-indicator-start and .dropdown-item-indicator-end for placing icons on either side of a dropdown-item and deprecated .dropdown-item-indicator

[pat270]

The pattern for icons on both sides:

<ul class="dropdown-menu dropdown-menu-indicator-end dropdown-menu-indicator-start">
    <li>
        <a class="dropdown-item">
            <span class="dropdown-item-indicator-start">
                <svg></svg>
            </span>
            Text
            <span class="dropdown-item-indicator-end">
                <svg></svg>
            </span>
        </a>
    </li>
</ul>

The pattern for icons on left:

<ul class="dropdown-menu dropdown-menu-indicator-start">
    <li>
        <a class="dropdown-item">
            <span class="dropdown-item-indicator-start">
                <svg></svg>
            </span>
            Text
        </a>
    </li>
</ul>

The pattern for icons on right:

<ul class="dropdown-menu dropdown-menu-indicator-end">
    <li>
        <a class="dropdown-item">
            Text
            <span class="dropdown-item-indicator-end">
                <svg></svg>
            </span>
        </a>
    </li>
</ul>

[matuzalemsteles]

hey @pat270, we'll have to modify the markup in ClayDropdown too, right?

[pat270]

@matuzalemsteles yes, clay-dropdown needs an update, but it will still work the old way. Also added docs.

[matuzalemsteles]

ok, thanks a lot @pat270. I'll create an issue to update the markups then.