Slack Integration (#170)

* slack integration

* recomment server variables

* recomment server variables

config/initializers/slack.rb

@@ -0,0 +1,36 @@
+# BigBlueButton open source conferencing system - http://www.bigbluebutton.org/.
+#
+# Copyright (c) 2016 BigBlueButton Inc. and by respective authors (see below).
+#
+# This program is free software; you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free Software
+# Foundation; either version 3.0 of the License, or (at your option) any later
+# version.
+#
+# BigBlueButton is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+# PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with BigBlueButton; if not, see <http://www.gnu.org/licenses/>.
+
+def uri?(string)
+  uri = URI.parse(string)
+  %w( http https ).include?(uri.scheme)
+rescue URI::BadURIError
+  false
+rescue URI::InvalidURIError
+  false
+end
+
+if !ENV['SLACK_WEBHOOK'].nil? && !ENV['SLACK_WEBHOOK'].empty? && uri?(ENV['SLACK_WEBHOOK']) then
+  # Initialize the slack notifier.
+  Rails.application.config.slack_notifier = Slack::Notifier.new ENV['SLACK_WEBHOOK'] do
+    defaults channel: ENV['SLACK_CHANNEL'],
+             username: "BigBlueButton",
+             icon_url: 'https://avatars3.githubusercontent.com/u/230228?v=3&s=200'
+  end
+else
+  # Initialize it to nil (slack not configured)
+  Rails.application.config.slack_notifier = nil
+end