Output list of failed hosts in a format that can be used

[amaxine]

List of failures should be followed by outputting the list in a format that can be easily reused for rerunning the task on just those nodes.

E.g. after

[2019-08-01 12:26:48] <local> ERROR - 	TASK failed on HOST_A
[2019-08-01 12:26:48] <local> ERROR - 		Error installing X at /usr/local/share/perl/5.26.1/Rex/Pkg/Base.pm line 80.
[2019-08-01 12:26:48] <local> ERROR - 	TASK failed on HOST_B
[2019-08-01 12:26:48] <local> ERROR - 		Error installing X at /usr/local/share/perl/5.26.1/Rex/Pkg/Base.pm line 80.

Have a List of failed hosts: HOST_A HOST_B