Align slackr handler to changes in web hook handler
Align slackr handler to changes in web hook handler

Specifically the commits
https://github.com/rackspace-cookbooks/chef-slack_handler/commit/4a0be03
e6d65f07cfe13eb1218aeb44e8ae417e9 and
https://github.com/rackspace-cookbooks/chef-slack_handler/commit/333eeee
df7c8d9030a5cb2bd4694c665711f4d56

c-knowles/chef-slack_handler,c-knowles/chef-slack_handler,rackspace-cookbooks/chef-slack_handler,rackspace-cookbooks/chef-slack_handler