Receive $viewValue in the ngModel for uiMask

Use the option: model-view-value="true" to make the directive return
masked ($viewValue) value in the model.
Ex: <input ng-model="model" ui-mask="(999) 999-9999"
model-view-value="true">
Merge pull request #137 from andyvr/newbranch

Receive $viewValue in the ngModel for uiMask