Improvements to Create User & Admin form in Admin

Several improvements needs to be done on Create User & Admin forms to better accommodate needs of the system:

[DEL][B]1.[/B] Make "Login" field as read-only when "Use Emails As Login" is enabled. However, we still need to display the actual data that user inputs (as he types) in the Email field in Login field as well.

It would be great if we can make the field grayed out (ie. disabled) so it's clear that fields is read-only.[/DEL]
Because of related task.

[B]2.[/B] Create new "generate" button next to Password field which will generate and populate both "Password" and "Re-enter Password" with the password.

However we still need to show the new password in both fields - "Password" and "Re-enter Password" so it's better to make them regular text fields so it's visible.

[B]3.[/B] Add new "Email Password to User" check-box field right after "Re-enter Password" field.

By default new field should HIDDEN since we can't restore user password once it's encoded.

This field will be:

a. VISIBLE when adding NEW User or Admin + "Assign password automatically" setting is Off.

b. VISIBLE + CHECKED by default when adding NEW User or Admin + "Assign password automatically" setting is On

c. User Admin wants to change the passwords either by clicking on "Generate" or start typing in

In result if new "Email Password to User" field was On AND user/password was CREATED or CHANGED we should send out new email event with new user details.