- Maps 1 to 1 with container's networking stack
- It holds container's specific nw options which
before were incorrectly owned by Endpoint.
- Sandbox creation no longer coupled with Endpoint Join,
sandbox and endpoint have now separate lifecycle.
- LeaveAll naturally replaced by Sandbox.Delete
- some pkg and file renaming in order to have clear
mapping between structure name and entity ("sandbox")
- Revisited hosts and resolv.conf handling
- Removed from JoinInfo interface capability of setting hosts and resolv.conf paths
- Changed etchosts.Build() to first write the search domains and then the nameservers
Signed-off-by: Alessandro Boch <aboch@docker.com>