based on successive failed login attempts

Description: This patch introduces a new audit plugin named
             connection_control. Using this plugin, it is
             possible to introduce an incremental delay in
             server response if consecutive failed login
             attempts for a given user account crosses user
             defined threshold value.

             It is possible to configure threshold value
             to trigger delay, minimum/maximum amount of
             delay through system variables introduced by
             connection_control plugin.

             This patch also introduces a new information
             schema view through an information schema plugin,
             connection_control_failed_attempts_view. This view
             provides information about consecutive failed
             attempts for various user account.