Ask for a login name during account creation

This should resolve #6.

Fix smtp url for manually entered smtp servers

This fixes one half of #6.

Added all domains of gmx.net and zoho.com to domains.csv and fixed error in README.md

This is first working version of an added login query to the account
creation process. It fixes the first part of #6, but there still needs
to be more testing for the second part of that issue, which concerns
creating accounts with domains not listed in domain.csv.

replaced "my" with "by" in two lines

Update domains.csv: add fastmail.com

Domain additions