Add host attribute with default value 'logs'
Update metadata and README for host attribute
Use fatal! method to handle port attribute missing

Log a fatal error message to both STDERR and the Logger, exit the
application:
http://rubydoc.info/gems/chef/Chef/Application#fatal%21-class_method
Merge branch 'add-host-attribute' of https://github.com/madwork/papertrail-rsyslog
Update tests for logs2 support