fix select object array child columns

of type string on system tables
Merge pull request #1165 from crate/m/sysobjectarrayrefs

fix select object array child columns
documentation for zero downtime cluster upgrade
added graceful_stop cluster settings
documentation for graceful_stop cluster settings
add SQLService that handles disabling of SQL transports
disable http for SQLServiceTest
changed implementation of global settings
load SQLService asEagerSingleton

otherwise re-enable won't work as it will load a new
instance of the service in InternalNode#start()
remove graceful_stop.is_default setting

it's not possible to support it
correct setting name in cluster-upgrade docs
document zero downtime upgrade requirements
also remove graceful_stop.is_default from set reference
update cluster upgrade docs
upgrade es upstream

in order to linearize cluster state updates in Deallocators
reintroducing the cluster.graceful_stop settings
upgrade es upstream

for increased deallocation loglevels
update changes
update cluster_upgrade

to point users to the logs of their deallocating nodes
remove stale debug log