Correctly handle no user data for mobile number input

[dirkcuys]

@s-kennedy I see you updated the mobile input here eabbe7b. This caused a problem when not entering a mobile number, since "+1" would be sent to the server which would make validation fail.

For now I've worked around the issue by adding back the hidden input that stores a cleaned up phone number 102e564. Maybe you can think of a cleaner solution?

[s-kennedy]

Looking into this further, it looks like the hidden field is the way to go for now... unless we want to fork the component repo and change the way it sets the input value. Probably more work than it's worth. Another problem though is that autocomplete messes up the country code selection. There's already an issue created for this: mukeshsoni/react-telephone-input#201. How much of a problem is this?

[shinysticker]

A fix for the autocomplete issue would be appreciated!