[client] base_ajax,hatohol_connector: Use POST mehtod for login to avoid exposing user name/password.

It is very bad to expose users' passwords in accesslogs.
To avoid that, let's use POST method for login.
Note that we always need to set cookie for the token to cope
with CSRF protection.

Signed-off-by: YOSHIFUJI Hideaki <hideaki.yoshifuji@miraclelinux.com>
[client] base_ajax,hatohol_connector: Use X-CSRFToken header instead of form data.

Signed-off-by: YOSHIFUJI Hideaki <hideaki.yoshifuji@miraclelinux.com>