fix(collapse): Setting overflow back to visible in Collapse (#433)

This fix helped me resolve 2 issues - collapse now expands all the way and takes component height into consideration, and also popups like datepicker aren't "cut-off" on component's edge.
fixes #372

components/collapse/collapse.component.ts

@@ -120,6 +120,7 @@ export class Collapse implements OnInit {
           .onComplete(() => {
             this.isCollapse = true;
             this.isCollapsing = false;
+            this._el.nativeElement.style.overflow = 'visible';
           });
       }, 4);
   }