Next

Much of this should be in the line of previous commits: cleanup and simplify.

Complete list by topic (from trivial to more important):

- better error conditions handling:
 * https://github.com/docker/docker-registry/commit/6b87fd19b08d03eddc1aa2e2cb1d5dc5bd322b8d
 * https://github.com/docker/docker-registry/commit/b2886c494a8f1efa0f1cc82ba2b777ff0439fc1a

- dotcloud cleanup:
 * https://github.com/docker/docker-registry/commit/f0aab993e9ad0007a477f56580288ccf4f5a928b

- first shot at making documentation less bloated and better
 *  https://github.com/docker/docker-registry/commit/2965945442771014f85d8a0cb6dbd646ff2d7641

- regression fixing (from previous commits / merge), pep8, tests fixing:
 * https://github.com/docker/docker-registry/commit/1f0d3145989a7f334aa790d092b98e023e2305a1
 * https://github.com/docker/docker-registry/commit/7b3b55d226e750349cd9278c00dd7c79038fb231
 * https://github.com/docker/docker-registry/commit/4b374fbd4a42f68a64e0641ef6f3b69933208c59
 * https://github.com/docker/docker-registry/commit/e40db180ba2aed3c284d62218ab829c2ea74194c
 * https://github.com/docker/docker-registry/commit/0b2018b8c2513dcab7bb25399ed4701c2a5ec8eb
 * https://github.com/docker/docker-registry/commit/a33e1341bb41137091ff8afbb7b7781e67ec76e3

- enhanced, more isolated abstractions for extras (including reformulating CORS as an extra):
 * https://github.com/docker/docker-registry/commit/f12665d06557b5044ec81dea8fb4a01cbb518b0a
 * https://github.com/docker/docker-registry/commit/83a7a04a258927d40b1fc619833c147a526443f3
 * https://github.com/docker/docker-registry/commit/52b6fafbb30744ec1444b7c0d23366d3a9712772
 * https://github.com/docker/docker-registry/commit/5c6bee79f0889806b8109d072029e464b3dc146d

- simplify debugging infos (and removed extraneous infos)
 * https://github.com/docker/docker-registry/commit/0570610d9f1ef7acfed5e00d34b5fa608bd9edcf
 * https://github.com/docker/docker-registry/commit/eab27be7d89654b320d5c1e73a014ecc075ea2d2

- refactored run/wsgi
 * https://github.com/docker/docker-registry/commit/c054d03a253de2ede9ab321a3171955d4a4ff6d6
 * https://github.com/docker/docker-registry/commit/e23e20c1b97b474a0ea2fd697e19b479420e5829

If search_backend is None, the endpoint is not imported (https://github.com/docker/docker-registry/blob/next/docker_registry/wsgi.py#L24)