Remove # from the debug output

The # must be part of the channel name assigned to the attribute else the channel is not recognized by Slack.
add fail_only support and detail options
update README
Merge pull request #4 from Sauraus/patch-1

Remove # from the debug output
Merge remote-tracking branch 'origin/master' into failures_and_detail

Conflicts:
	files/default/slack_handler.rb
Merge pull request #5 from Sauraus/failures_and_detail

Failures and detail