graduate oslo.context

importing the lib: https://review.openstack.org/#/c/132877/

Work items:
Create Initial Repository: DONE
Update MAINTAINERS in incubator with status and name: DONE
Run graduate.sh: DONE
Fix the output of graduate.sh: DONE
Use cookiecutter template to make a new project: DONE
Sync tools from incubator: DONE
Publish git repo: DONE
Oslo team review new repository: DONE
openstack-infra/project-config - gerrit/projects.yaml: DONE
openstack-infra/project-config - gerrit/acls/openstack/project-name.config: DONE
openstack-infra/project-config - jenkins/jobs/projects.yaml: DONE
openstack-infra/project-config - zuul/layout.yaml: DONE
openstack-infra/project-config - gerritbot/channels.yaml: DONE
Update Gerrit Groups and ACLs: DONE
openstack-infra/devstack-gate - devstack-vm-gate-wrap.sh - https://review.openstack.org/#/c/135093/ : DONE
openstack/requirements projects.txt: DONE
openstack/governance reference/programs.yaml: DONE
Update list of libraries on Oslo wiki page: DONE
Create Launchpad project: DONE
Create Launchpad bug tracker: DONE
Create Launchpad blueprint tracker: DONE
Change owner of Launchpad project: DONE
Make the library do something: DONE
Add registry management logic - https://review.openstack.org/#/c/135643/: DONE
Update the README.rst: DONE
Give openstackci Owner permissions on PyPI: DONE
Tag a release: DONE
Remove graduated code from oslo-incubator - https://review.openstack.org/#/c/148545/: DONE
Update oslo-incubator/update.py to not rewrite references to the library: DONE
openstack/requirements - global-requirements.txt - https://review.openstack.org/140141: DONE
Document Migration Process: TODO
openstack-dev/devstack - lib/oslo - https://review.openstack.org/#/c/140112/ : DONE
openstack-dev/devstack - stackrc: DONE
Update project list on docs.openstack.org: DONE