Enhanced arguments handling

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <olivier@docker.com> (github: dmp42)
Pin hacking to fix tests

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <olivier@docker.com> (github: dmp42)
Enhanced arguments handling

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <olivier@docker.com> (github: dmp42)
Bump core version

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <olivier@docker.com> (github: dmp42)
Enhance filtering on the driver interface

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <olivier@docker.com> (github: dmp42)
Better (index-based) validation

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <olivier@docker.com> (github: dmp42)
Fix parameter naming

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <olivier@docker.com> (github: dmp42)
Revert hacking temporary pinning from 0.8

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <olivier@docker.com> (github: dmp42)
Merge pull request #539 from docker/0.8-backport

0.8 backport
Dont rewrite content identical to cached data
Remove private image endpoints

The private image endpoints were broken, unused,
and undocumented.

Signed-off-by: Eric Windisch <eric@windisch.us>
Merge pull request #546 from ewindisch/remove_private_endpoints

Remove private image endpoints
fix parenthesis for default environment variables
refs #484 to configure CORS
Merge pull request #549 from visualphoenix/bugfix/env_defaults

fix parenthesis for default environment variables
Merge pull request #544 from docker/lru_oprimize_put_content

Dont rewrite content identical to cached data
fix gunicorn arguments so that docker-registry can start without error
Merge pull request #484 from S1E11/master

to enable CORS tag API
Fix bugs when using MySQL as index database

1. MySQLdb will raise ProgrammingError when table doesn't exists. Use engine.has_table to check whether table exists for compatible
2. VARCHAR requires a length on dialect mysql. String length limit is according to [Docker Hub's limit](https://registry.hub.docker.com/account/repositories/add/) and [docker's valid namespace and repo regex](https://github.com/docker/docker/blob/master/registry/registry.go#L214)
Ignore pedentic hacking warning

- H803 disables verifying that commit message doesn't end with a dot

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <olivier@docker.com> (github: dmp42)