WL#483: change RESET/PURGE MASTER syntax

Affects: Server-7.1   —   Status: Un-Assigned   —   Priority: Medium

rename RESET MASTER      -> RESET BINARY LOGS or DELETE BINARY LOGS
rename PURGE MASTER LOGS -> DELETE BINARY LOGS to 'xxxx' (4.1)

will use:

DELETE BINARY LOGS
DELETE BINARY LOGS TO 'xxx'