Add write_acks field in table_config
Rename namespace_metadata->tables/table_metadata, database_metadata->tables/database_metadata
Factor out ack-checking logic into new write_ack_config_checker_t class.
Update readiness indicators in table_status now that we have proper write ack settings.
Add durability field to table_config
First draft of interface.table_acks_durability; not tested yet.
Fix some stupid mistakes in interface.table_acks_durability
Acks+durability unit test works up to the point where it needs the ability to permanently remove servers.
Merge branch 'reql_admin' into tim/3066-acks-durability
Make the rest of the interface.table_acks_durability test work.
Don't let the user set unsatisfiable write acks in config, and show an issue if it happens anyway through servers being permanently removed.
Make reconfigure() work properly with durability/ack settings, and fix interface.table_reconfigure test.
Fix interface.permanently_remove by setting tables' write durability to 'single'
Declare single-parameter constructors explicit; fix typo in comment.
Merge branch 'tim/3066-acks-durability' into reql_admin