Added basic support for sending alerts to Slack.
- config additions
- alert additions/modifications (piggybacking on hipchat)
- model additions
- form additions
- south migration
Merged from labxio:slack-support (pull request #55)
Merge branch 'master' into slack_support
Added support for icon_url
Updated migration to support cabotapp_instance
remove unused variable
Modified slack properties
fixed slack support
Merge branch 'master' into slack_support
Merge branch 'master' of github.com:arachnys/cabot
merge resolved
Merge pull request #2 from kaeawc/slack_support

Slack support