Support for recent versions of runC

[teddyking]

When running ctop with a recent version of runC, the following error is generated:

failed to read container: json: cannot unmarshal object into Go struct field Config.capabilities of type []string

I think this is probably because ctop is using runC version 0.1.1 (which is now over a year old). In 0.1.1 capabilities are defined as a []string whereas in newer versions they are their own separate struct.

Would it be possible to support the latest runC version? Happy to open a PR for this if yes.

[bcicen]

@teddyking I'd happily accept a PR for latest runC support.

0.1.1 is still the latest release available via major distros; however, we can simply move support for this older version to its own branch/build.