Feature - Add multi-state support for uiSrefActive

[jutaz]

This is a quick, interface compliant addition to uiSrefActive to allow for multiple, non-sibling states to activate same class in uiSrefActive. For example:

<div ui-sref-active="{'active': ['owner.**', 'admin.**']}">
  <a ui-sref-active="active" ui-sref="admin.roles">Roles</a>
</div>

Will now be active for when owner.** state is entered, but also admin.**. This makes it much easier to have select parallel states share same class name without resorting to writing boilerplate code to handle that.

Closes #2524