docs(README): add troubleshooting for 'not reachable' peers

Adds section with an explanation and remediation steps for the
'All the given peers are not reachable' error.
Merge pull request #968 from deis/no_peers_readme

docs(README): add troubleshooting for 'not reachable' peers
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(router): support for multiple routers

This commit adds functionality to the Makefile to launch multiple
routers, which is the first step towards a HA Deis installation.

Additional routers can later be added to an existing cluster by setting
DEIS_FIRST_ROUTER to start the router numbering at something other than 1.

Note that load balancing / DNS records must still be set up manually.

We also have the router publish its host:port to the namespace
/deis/routers/$HOST, as we have the possibility of multiple routers
in the cluster.

closes #922