fix(multiple): formatter binding

[dimirc]

• Prevent $select.selected with incorrect values from formatter
  Closes null values in ng-model after changing ng-model programmatically on multiselect #739
  Fixed plunker
• If item not found on current available lists, add it directly to selected
• Change comparison to angular.equals()
  Closes if (result == value) to "if (angular.equals(result,value)){" #410

[dimirc]

@renanlecaro commented

I got into some trouble when modifying the model outside of ui-select too
http://plnkr.co/edit/Wboo1fiePaLHKX0eHjxI?p=preview
It looks like it's more of a one way binding than a 2 ways : adding / removing elements with ui-select works well, but the digest cycle of the directive is not always triggered.

Also this PR should solve it now. Updated plunker

[KKrisu]

Looks good for me.
I think you can include unit test I wrote in PR #740 which covers issue #739

[renanlecaro]

Okay this is weird, It does work on the plunkr but not in my app, and that's because of the angular version. With the latest angular version, the ui-select list updates every two adds

http://plnkr.co/edit/s4M6U89aXYMCDfCUlk0x?p=preview

(i modified the plunks to add unique tags to the list)

[dimirc]

@renanlecaro I did some additional changes. Check updated plunker with angular v1.3.14

[KKrisu]

@dimirc I think would be good to add unit test for issue #739, which I wrote in closed PR
https://github.com/angular-ui/ui-select/pull/740/files#diff-26736c4d2d5d1e4c66b6e602618cb367R1694