refactor server_privileges.php: split long code to functions
rename some functions
update function name
fix code style
refactor PMA_updateDataForDBInfo, moving parameter into function
refactor function PMA_updateDataForChangeOrCopyUser
refactor function PMA_updateDataForAddUser
fix code styles
rename function for better readability
remove unneeded parameter and return values
Merge pull request #581 from xmujay/0809_serverprivileges

refactor server privileges