Password update for users in Spock

For RBAC, we need to be able to update user passwords.

Password update (through REST and UI) like normal folks – Provide Old Password to Update Password. 

This is different that password reset, where were reset the password through e-mail.

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Generally update of password is done by the user, but reset is done by the admin.

Note: Administrator should be able to change his password via the same UI