Update .mailmap and AUTHORS
Fixed a typo.
Added a note to the README about PuppetDB being required in order to use the icinga2::object defined types as exported resources.
Make the 'true' bold for additional emphasis.
Added Debian 7 support

Signed-off-by: Nick Chappell <nick@intronic.org>

Taken from: https://github.com/Icinga/puppet-icinga2/pull/9

refs #7264, https://dev.icinga.org/issues/7264
Fix for wrong package name in Debian 7

Signed-off-by: Nick Chappell <nick@intronic.org>

Taken from: https://github.com/Icinga/puppet-icinga2/pull/9

refs #7264, https://dev.icinga.org/issues/7264
Fix on metadata #7264

Signed-off-by: Nick Chappell <nick@intronic.org>

Taken from: https://github.com/Icinga/puppet-icinga2/pull/9

refs #7264, https://dev.icinga.org/issues/7264
Changelog update.
Added a contributing section with instructions for how to submit pull requests on GitHub.