Remove nsinit main calling pkg

Signed-off-by: Michael Crosby <michael@docker.com>
Make nsinit package main only

Signed-off-by: Michael Crosby <michael@docker.com>
Improve execin to support registering funcs

This also changes the functionality of the default exec in to just be an
existing func that is called than handles the implementation to exec a
user user's process inside the container.  This implements this
functionallity in nsinit but is a base for how we will be handling these
types of features inside docker.

Signed-off-by: Michael Crosby <michael@docker.com>
Add ip func example for listing namespace interfaces

Signed-off-by: Michael Crosby <michael@docker.com>
Cleanup and rename loadContainer to loadConfig

Signed-off-by: Michael Crosby <michael@docker.com>
Reuse exec cli function and strip nsenter- from funcs

Signed-off-by: Michael Crosby <michael@docker.com>
Merge pull request #155 from crosbymichael/execin-func

Implement execin by using registered functions