Add privileges to catalogs

Add users and privileges to each catalog.
The super user of the 'def'' catalog is granted the CATALOG privilege that allows one to
change catalog with 'use catalog catalog_name'

When running with catalogs, the 'def' users are the only one that can get the following privileges:
CATALOG_ACL |
SHUTDOWN_ACL |
CREATE_TABLESPACE_ACL |
REPL_SLAVE_ACL |
BINLOG_MONITOR_ACL |
BINLOG_REPLAY_ACL |
BINLOG_MONITOR_ACL |
CONNECTION_ADMIN_ACL |
REPL_SLAVE_ADMIN_ACL |
BINLOG_ADMIN_ACL |
BINLOG_REPLAY_ACL |
SLAVE_MONITOR_ACL |
BINLOG_MONITOR_ACL |
REPL_MASTER_ADMIN_ACL;

Things to do :

• Privileges globals should be stored in catalog
• acl_init() should be run for all catalogs (as part of catalog->late_init())
• grant_init() should be run for all catalogs
• acl_reload() should only be run for current catalog
• In case of SIGHUP it should be run for all initialized catalogs
  see reload_acl_and_cache() and late_init_all_catalogs()