feature: add rich container mode

[wangforthinker]

1.Describe what this PR did

In pouch, we can start container in rich container mode by cli flag or API.
If by pouch client, we can set --rich flag to set rich container mode, and set --rich-mode to select which manner to init container, we support systemd, /sbin/init and dumb-init to init container.
If set dumb-init to init container, please install dumb-init in machines, https://github.com/Yelp/dumb-init/tree/v1.2.1
if set systemd or /sbin/init, we need to install systemd or /sbin/init in image.
Otherwise, we need to install runc modified by us to support it, referring to https://github.com/alibaba/runc/tree/v1.0.0-rc4-1.

2.Does this pull request fix one issue?
fixes #25

3.Describe how you did it

4.Describe how to verify it

5.Special notes for reviews

[pouchrobot]

ping @wangforthinker

CI fails according integration system.
Please refer to the CI failure Details button to corresponding test, and update your PR to pass CI.

If this is flaky test, welcome to track this with profiling an issue.

build url: https://travis-ci.org/alibaba/pouch/builds/346668411
build duration: 1150s

[Letty5411]

the fail test is flaky test, unrelated to this PR.