Login field is case sensitive and untrimmed

[krav]

I'm trying out Casdoor, and getting complaints from a significant percentage of users having trouble logging in.

Particularly people register with "email@example.com" only to later try to log in as "Email@example.com" or "email@example.com "--and getting rejected as a non-existent account. Sometimes they proceed to try and register again, being told that the account already exists.

Can we add optionally downcasing and trimming the username field?

(Using postgres as a backing database btw, this is possibly case insensitive in others?)

[casbin-bot]

@tangyang9464 @JalinWang @imp2002

[hsluoyz]

Use the existing config:

casdoor/conf/app.conf

Line 18 in 21c151b

isUsernameLowered = false