materialize="material_select" multiple collapses on item select #422

Actual behavior:

When select item in multiselect dropdown list it's redraws component and dropdown collapsed after it

Expected behavior

Same behavior as on materializecss.com. When select item in dropdown it's not collapsed.

Demo link:

https://infomedialtd.github.io/angular2-materialize/#/Forms

Note:

It's redraws multiselect because reference between old and new value changed. If on get/set return/set same array with modified content - component will not redraw and dropdown will not be collapsed