Add fs.NotifyOnOOM for out-of-memory notifications

Docker-DCO-1.1-Signed-off-by: Bernerd Schaefer <bj.schaefer@gmail.com> (github: bernerdschaefer)
Updated libcontainer subpackage dependencies. Most subpackages now do not depend on their parent ('libcontainer') package. 'namespaces' and 'nsinit' still do.
'namespaces' need to refactored a bit more to move the API part of it to 'libcontainer' package and keep the namespace specific code inside that package.
This change is not expected to break docker.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Rename MountSpec to MountConfig.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Added DropCapabilities() and DropBoundingSet() API to libcontainer.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Reuse internal mount.Mount in the API.
Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Remove 'Context' type from the libcontainer API. It will be a generic map with string key and value henceforth.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Minor fixes.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Addressed more comments.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Use internal types in the API instead of duplicating the types.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Use internal types in the API instead of duplicating the types.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Fix veth json and tags
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Make MountConfig on container a pointer

Also add unit test for container json files to ensure that the mount
config is read and device nodes are validated.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Merge pull request #1 from crosbymichael/refactor-fixes

This fixes mount and networking
Fix cross compile for network and node pkgs
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Merge pull request #2 from crosbymichael/fix-crosscompile

Fix cross compile for network and node pkgs
Merge pull request #41 from vishh/refactoring

Refactoring libcontainer to avoid cyclic dependencies in the future.
Rename Container -> Config.

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)
Merge pull request #39 from vmarmol/rename-container

Rename Container -> Config.
Fix nits on chan direction and defer

Closes #9
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Remove generic context and replace with fields
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)