Use e-mail for Fever auth instead of username

[passiomatic]

Fever API uses email instead of username to perform user authentication:

$email  = 'you@yourdomain.com';
$pass   = 'b3stp4s4wd3v4';
$api_key = md5($email.':'.$pass);

Switch to email when creating the API key and allow to log into Coldsweat using username or email.