fix gunicorn arguments so that docker-registry can start without error
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)
Fix auth_basic exemption in sample nginx.conf
Add original comments to included nginx configuration.
Merge pull request #555 from irachex/mysql

Fix bugs when using MySQL as index database
Fixed get_tags whe using storage_path
Added test
Merge pull request #548 from visualphoenix/bugfix/gunicorn_wont_start

BUGFIX: modify run.py gunicorn arguments so docker-registry can start without error
blacklist backports.lzma v0.0.4

backports.lzma recently bumped up to v0.0.4, adding namespace support
to the package. However, they forgot to call declare_namespace() in
their __init__.py. This causes pip install failures when running

    pip install file:///docker-registry#egg=docker-registry

From inside the Dockerfile.
Merge pull request #573 from deis/hotfix-pin-lzma

blacklist backports.lzma v0.0.4
Bumped stable version
Merge pull request #553 from docker/486-get-tags

Fixed get_tags whe using storage_path
Add image to tag_deleted signal payload

Add image to tag_deleted signal payload. This is useful for things
such as a refcount extension, which needs to know the image that was
associated with the deleted tag so refcounts can be updated accordingly.
CONTRIBUTING.md: Rename from 'CONTRIBUTE.md'

To match GitHub's conventions [1].  With this change, folks will get
links to the contributing docs when they open a new issue or
pull-request using GitHub's web UI.

[1]: https://github.com/blog/1184-contributing-guidelines
CONTRIBUTING.md: Point closed-source hub issues to support-index@

To give @shin- a break from redirecting people ;).
Merge pull request #579 from wking/contributing

CONTRIBUTE.md → CONTRIBUTING.md and a support-index@ reference
Merge pull request #577 from ncdc/add-image-id-to-tag-deleted-signal

Add image to tag_deleted signal payload
Merge pull request #564 from Precis/nginx_auth_exemption

Fix auth_basic exemption in nginx.conf sample
Fix loose deps

- hard pin dynamically inserted libraries
- fix deps loose mechanism so that:
 * short versioned libraries are scopped as the rest
 * additional restrictions (blacklists for eg) are ported over
merge search results between local and index route

Correcting for dmp42 comments on irc