User is unable to log in when entering space after the login

[kolszewska]

Current Behavior

Entering a space after providing login results in "Field is required". User is not able to log in due to "Log in" button being disabled.

Expected Behavior

Entering a space at the end should have no effect and should be ignored by both backend and frontend. Or it should be handled otherwise (TBD)

Steps to Reproduce the Problem

1. Go to login page,
2. Write a login and enter space at the end
3. Click somewhere on the page (so that the field will not be focused)