Change a few rules regarding registration (login regex, password length).

src/requests/register.cr

@@ -17,7 +17,7 @@ class AuthD::Request
 				return Response::ErrorAlreadyUsedLogin.new
 			end
 
-			acceptable_login_regex = "[a-zA-Z][-_ a-zA-Z0-9']+"
+			acceptable_login_regex = "[a-zA-Z][-_ a-zA-Z0-9']*[a-zA-Z0-9]"
 			pattern = Regex.new acceptable_login_regex, Regex::Options::IGNORE_CASE
 			return Response::ErrorInvalidLoginFormat.new unless pattern =~ @login
 
@@ -35,7 +35,7 @@ class AuthD::Request
 			end
 
 			# In this case we should not accept its registration.
-			return Response::ErrorPasswordTooShort.new if @password.size < 20
+			return Response::ErrorPasswordTooShort.new if @password.size < 15
 			return Response::ErrorPasswordTooLong.new  if @password.size > 100
 
 			uid = authd.new_uid