Install the Debian keys. Fixes #359.
Also install Debian keyring on Ubuntu.

Just in case.
Stop complaining about `$` needing escape
Add Liu Xiaohui(@oreh) to AUTHORS
Add quotes around `apache-libcloud>=$_LIBCLOUD_MIN_VERSION`
Update ChangeLog
Add the backports key to keyring. Update after installing keyring.
Merge pull request #360 from s0undt3ch/develop

Install the Debian keys