fix ssh_known_hosts config
run well for both dokku and dokku-alt
Merge pull request #4 from eduvo/faria

run well for both dokku and dokku-alt
[BUGFIX] Only source if dokku-alt is present
Merge pull request #5 from cedricziel/fixNonDokkuOld

[BUGFIX] Only source if dokku-alt is present
Merge pull request #6 from RobinQu/master

[BUGFIX] Fix ssh_known_hosts config
Merge pull request #1 from cedricziel/master

merge from upstream