Change single-dash flag usage to double-dash

The single-dash long-form flag usage is deprecated.

Docker-DCO-1.1-Signed-off-by: Nathan LeClaire <nathanleclaire@gmail.com> (github: nathanleclaire)
Fix add hang when dest is .

Fixes #3960
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
adding test for hanging ADD src .

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
Merge pull request #25 from tiborvass/3960-add-file-hangs

adding test for hanging ADD src .
Merge pull request #5997 from crosbymichael/add-hang

Fix add hang when dest is .
Merge pull request #5949 from nathanleclaire/patch-1

Change single-dash flag usage to double-dash
Add more required cgroup subsystems to check-config.sh (specifically, SCHED for cpu and CPUACCT for cpuacct)

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Fix a few issues.

-single-dash => --double-dash for a few flags, and also there was a missing "B", as in "Container B".

Docker-DCO-1.1-Signed-off-by: Nathan LeClaire <nathan.leclaire@gmail.com> (github: nathanleclaire)
Merge pull request #6012 from tianon/check-config-cgroup-subsystems

Add more required cgroup subsystems to check-config.sh
Merge pull request #5952 from nathanleclaire/patch-2

Fix a few issues.