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
docs(*): add bare-metal guide

Adds some light documentation around bare metal provisioning.

closes #730
Merge pull request #979 from deis/baremetal_docs

docs(*): add bare-metal guide
Merge pull request #969 from deis/multiple_routers

feat(router): support for multiple routers
feat(router): route to controller by default

This routes all requests made to the domain redirect to the
controller.

TESTING: rebuild the router with this change:

    $ make -C router build restart

then, try to send a GET request to both local.deisapp.com and
www.local.deisapp.com. They should both redirect to the controller's
home page.
fix(router): remove www prefix from controller

We want to retain the use of the application subdomains to
just that, the applications. removing the optional `www` regex
from the deis-controller entry on the router fixes this. The
controller is now only routable to the TLD for the cluster.