slap/standalone: support setting multi-master in slapos.cfg

This allow to use standalone slapos with some requests being forwarded
to another slapos master. The intended use case is to make have frontend
requests forwarded to "real" slapos master when embedding slapos in
theia or slaprunner.
21 jobs for feat/standalone_multimaster in 0 seconds
Status Job ID Name Coverage
  External
canceled SlapOS.Eggs.UnitTest-Jerome.Python2

74:01:02

canceled SlapOS.Eggs.UnitTest-Jerome.Python3

74:01:22

passed SlapOS.Eggs.UnitTest-Jerome.Python2

01:00:23

passed SlapOS.Eggs.UnitTest-Jerome.Python2

01:29:19

passed SlapOS.Eggs.UnitTest-Jerome.Python2

01:15:24

failed SlapOS.Eggs.UnitTest-Jerome.Python2

01:55:55

passed SlapOS.Eggs.UnitTest-Jerome.Python2

01:05:02

passed SlapOS.Eggs.UnitTest-Jerome.Python2

01:53:02

passed SlapOS.Eggs.UnitTest-Jerome.Python2

01:04:34

passed SlapOS.Eggs.UnitTest-Jerome.Python2

01:17:33

passed SlapOS.Eggs.UnitTest-Jerome.Python2

01:06:58

failed SlapOS.Eggs.UnitTest-Jerome.Python2

01:07:43

passed SlapOS.Eggs.UnitTest-Jerome.Python2

02:06:59

failed SlapOS.Eggs.UnitTest-Jerome.Python2

01:52:53

passed SlapOS.Eggs.UnitTest-Jerome.Python3

02:15:03

passed SlapOS.Eggs.UnitTest-Jerome.Python3

17:15:05

passed SlapOS.Eggs.UnitTest-Jerome.Python3

00:41:51

passed SlapOS.Eggs.UnitTest-Jerome.Python3

15:09:42

failed SlapOS.Eggs.UnitTest-Jerome.Python3

32:43:09

passed SlapOS.Eggs.UnitTest-Jerome.Python3

97:06:22

passed SlapOS.Eggs.UnitTest-Jerome.Python3

01:24:38