Change the place holding text for required fields in Collector for Android

[AndrewMunn1]

If a field is required (does not allow null values) and has a domain applied to it, the field alias is used as a place holder in Collector for Android.  This can be confusing because it is not clear which is the field name and which is the place to enter the value.  

It would be less confusing if the place holder was some generic text like "Enter Value" or if it was blank.