Reset impersonating state on process logout

[zorn-v]

Currently, if you have expired impersonate token and you get 401 server response for refresh user, you'll stuck in semi-impersonating mode. E.g. if you enter any valid credentials without refreshing page, token will be saved in tokenImpersonateKey. So you are become impersonating yourself without default token. Return to normal state avail after unimpersonate (which work like logout now) and relogin.