WFLY-2850 External authentication (includes Undertow 1.0.6.Final)
Merge pull request #6180 from stuartwdouglas/WFLY-2850

[8.1.0] WFLY-2850 External authentication (includes Undertow 1.0.6.Final)
WFLY-1101 Add XML format for timer service

The existing format is still supported, and will be converted to XML on first read.