Move 'GraphiteWriter already connected' to debug log.

Refs #6070
Fix compatibility with older versions of CMake.

Fixes #6240
Fix the current zone master log message.

Fixes #6241
Fix cluster check output.

Fixes #6244
Documentation: Move ITL/Plugin Commands into Icinga 2 configuration.

Fixes #6245
Documentation: Add a better example for apply rules in monitoring basics.

Refs #5827
Documentation: Add a note on recovery notifications during downtime.

Refs #6228
Remove build dependency for postgresql84.

Fixes #5847
Documentation: Fix cluster config examples.

Fixes #6247
Documentation: Add a note for the vagrant demo vm to 'about' .

Fixes #6248
Build fix for Fedora.

Fixes #6250
Fix revision in version string.

Fixes #6231
Add description for the display_name attribute for services.

Fixes #6253
Fix PerfdataWriter config validation.

Fixes #6255
Use the right CheckResult object for commands.

Fixes #6260
Fix compiler warnings.

Fixes #5823
Fix logrotate config.

Fixes #6229
Fix invalid logrotate option.

Fixes #6265
Parse config files in a sorted order. (WIP)

Refs #5854