Put an __init__.py in devices_tests directory.
Put an __init__.py in devices_tests directory.

Otherwise unittest framework will fail to discover them.

This change should have gone in with commit
cd56287e7c2574e188a8dab6967e9f867aeba867.

Signed-off-by: mulhern <7b51bcf507bcd7afb72bf8663752c0ddbeb517f6@redhat.com>

vojtechtrefny/blivet,vpodzime/blivet,rhinstaller/blivet,rvykydal/blivet,rhinstaller/blivet,dwlehman/blivet,AdamWill/blivet,jkonecny12/blivet,AdamWill/blivet,rvykydal/blivet,vpodzime/blivet,dwlehman/blivet,jkonecny12/blivet,vojtechtrefny/blivet