Documentation: Clarify on which config tools are available

fixes #6909
Documentation: Fix naming s/central/master/

fixes #6878
Fix external command pipe: Too many open files

fixes #6916
Documentation: s/service\.description/service\.name/

refs #6918
Add context information for Graphite error messages

fixes #6898
DB IDO: Add endpoint_name to programstatus table

refs #6827
refs #6203
DB IDO: Add 'enable_ha' configuration flag

This feature is true by default. If disabled all cluster nodes in a high
availability zone will write to their own local database.

TODO: documentation, tests.

refs #6827
refs #6203
DB IDO: Delay connection in HA RunOnce mode

refs #6827
refs #6203
DB IDO: Add documentation for HA functionality

refs #6827
refs #6203
DB IDO: Add failover_timeout attribute

refs #6827