[WFLY-543] : Provide an operation to request service status report after server has been started

Adding the new command "read-boot-errors" available from core-service=management to list all operations that failed during boot.
It displays all boot errors with the failed operation and the failure description / exception of the error.
Jira: https://issues.jboss.org/browse/WFLY-543
Please don't use complex list return type.
errors are list of strings.
so .setReplyValueType(ModelType.STRING) will do, also console guys will appreciate it...