mask: Use $viewValue instead of $modelValue in initializeElement()
mask: Use $viewValue instead of $modelValue in initializeElement()

This fixes an issue when ui-mask is used together with other directives
that have $formatters modifying the $modelValue.

pedroso/ui-mask,RafaelTaranto/ui-mask,angular-ui/ui-indeterminate,zhaokunfay/ui-uploader,KingMario/ui-uploader,xml/ui-mask,graingert/ui-keypress,zhaokunfay/ui-mask,akhilshastri/ui-utils,angular-ui/ui-scrollpoint,zhaokunfay/ui-event,angular-ui/ui-scrollpoint,xuwupeng2000/ui-event,lu4/ui-mask,xuwupeng2000/ui-event,Queatz/ui-validate,zhaokunfay/ui-indeterminate,zhaokunfay/ui-scrollpoint,angular-ui/ui-event,HawkHouseIntegration/ui-mask,zhaokunfay/ui-indeterminate,aniellepizzo/ui-scrollpoint,zhaokunfay/ui-event,aniellepizzo/ui-scrollpoint,lith-light-g/ui-scrollpoint,zhaokunfay/ui-scrollpoint,NickTomlin/ui-mask,KingMario/ui-uploader,marbletravis/ui-mask,NickTomlin/ui-mask,modulexcite/ui-utils,mengshadow/angularjs,r0b-/ui-validate,zhaokunfay/ui-validate,angular-ui/ui-validate,saike/ui-mask,saike/ui-mask,zhaokunfay/ui-mask,zhaokunfay/ui-uploader,Mojility/ui-uploader,lu4/ui-mask,graingert/ui-jq,Mojility/ui-uploader,zhaokunfay/ui-validate,graingert/ui-utils,angular-ui/ui-uploader,lukepfeiffer10/ui-mask,lith-light-g/ui-scrollpoint,angular-ui/ui-event,HawkHouseIntegration/ui-mask,isaacplmann/ui-mask,marbletravis/ui-mask,isaacplmann/ui-mask,DexStr/ui-uploader,angular-ui/ui-utils,Queatz/ui-validate,angular-ui/ui-mask,angular-ui/ui-indeterminate,pedroso/ui-mask,r0b-/ui-validate,xml/ui-mask,lukepfeiffer10/ui-mask,graingert/ui-utils,graingert/ui-keypress,mengshadow/angularjs,RafaelTaranto/ui-mask,DexStr/ui-uploader,graingert/ui-jq