Rename `default.conf` to `twitter.conf`

This commit refs #96.
Create Sensu configuration file for `hipchat`.

This commit refs #96.
Add encrypted_data bag for hipchat notification.

This commit refs #96.
Create `default` handler set to notify via `twitter` and `hipchat`

This commit refs #96.
Merge pull request #96 from kazu634/id/96

[Sensu] default handlerでtwitter,hipchatに通知するようにする