feat(router): configurable gzip settings

Fixes #884
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