[HatoholLoginDialog] Make browsers remember a user name the password.

A mechanism to remember values in an input form depends on browsers.
In general, they seem to rember a user name and the password when
a submit button is clicked in a form tag.

So this patch also makes an input form in the login dialog.

I confirmed that it works on Google Chrome 36.0 and Firefox 31.0.
[HatoholLoginDialog] Validate values when browser automatically complete a form.
[HatoholLoginDialog] Don't validate the passowrd input field.

On Google chrome and Firefox, it seems that the change() event
doesn't happen when the password is automatically completed.
To improve usability, this patch remove the validation for
the password.
Merge pull request #361 from project-hatohol/passwd-remember

Passwd remember