More details for the user address field.

Users integrating with our platform frequently (most of the time)
attempt to update the address with a completely bohus value (like 'bla')
not realising that we do a lookup with google and split the value into
its components before saving.
Merge pull request #32 from everydayhero/md_explain_user_address_in_more_detail

PROPOSAL - more details for the user address field