truncate currently is just an hbase shell command
and it basically deletes the table and creates a new one.
using ACLs the user running truncate, must have rights to create a table.
(currently only "global granted" users can create tables)
truncate is supposed to be more like a "delete_all",
requiring just the ability to delete all the rows in the table.
should truncate be promoted to a master call to have its own ACL check?