Updating changlog and releases for 1.6
made enabled/disabled checks of apache2_module workable
Make sure distro variable is set if python-apt is installed

Fixes #7295
Close fds when running commands from the accelerate daemon

Fixes #7307
Add integration tests for group_by module. Fixed bug introduced by ansible/ansible#7273 while also fixing issue described in ansible/ansible#6953
Version bump for 1.6.1 release
Merge remote-tracking branch 'ansible/release1.6.1' into ACD