feat(router): configurable gzip settings

Fixes #884
chore(controller): update djangorestframework to 2.3.13

https://github.com/tomchristie/django-rest-framework/compare/2.3.12...2.3.13
chore(controller): update celery to 3.1.11

http://docs.celeryproject.org/en/latest/changelog.html#version-3-1-11
chore(controller): update redis to 2.9.1

https://github.com/andymccurdy/redis-py/compare/2.8.0...2.9.1
refactor(controller): removed unused ssh.py and its dependencies

We weren't using paramiko or pycrypto any longer.
fix(test): remove `-K` ssh-add option that isn't available on Linux

The Mac OS X version of `ssh-add` has the `-K` flag to update the
passphrase, but `ssh-add` in Ubuntu 14.04 LTS does not.
Merge pull request #971 from deis/integration-linux-fix

fix(test): remove `-K` ssh-add option that isn't available on Linux
Merge pull request #965 from johanneswuerbach/gzip-router

feat(router): configurable gzip settings
Merge pull request #943 from deis/python-updates

chore(controller): update celery, djangorestframework, redis
feat(dockerfile): improve dockerfile and procfile workflow

- add SHA, Procfile and Dockerfile to Build model (if available)
- fix operator precedence bug from deis/deis#890
- add container type check before scale operations (fixes #496)
- add uniqueness constraint check on container type/num
- use SHA in release summary if available
- auto-scale web=1 for heroku workflow, cmd=1 for docker workflow
- add tests for heroku and docker workflows, plus test for invalid process types
feat(builder): update builder to pass SHA/Procfile/Dockerfile (if available)
fix(announcer): detect first exposed port instead of hardcoding to 5000/tcp
fix(schema): remove uniqueness constraint on containers
fix(controller): only scale web=1 if procfile has web entry
fix(scale): move initial scaling logic to model, add tests
fix(migration): squash migrations, add newline
fix(builder): include default_process_types from .release
fix(deploy): rework initial deploy logic based on workflow
fix(flake8): resolve code formatting issues
fix(tests): close db connections during threaded execution

This appears to resolve https://code.djangoproject.com/ticket/22420
allowing us to get test coverage for threads executed within
TransactionTestCases.