fix(select): fix the unselection of model
fix(select): fix the unselection of model

Ensure that the choice being unselected really is in the model (to avoid
to splice with "-1" index, which will remove the last element of the
array).
Also, check with an `angular.equals` call to avoid to compare with
angular "things" in the objects

lumapps/lumX,lumapps/lumX,lumapps/lumX,lumapps/lumX