pkg: Add etcdcluster package

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
host/cli: Add init command for configuring the cluster

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
host: Default to 1-node etcd configuration if none is specified

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
host: Lookup default external IP

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
discoverd: Bump etcd connection attempts to 10 minutes

When starting a v0.5 cluster for the first time it can take a while for
all of the nodes to show up.

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
host: Bump discoverd connection attempts to 10 minutes

When starting a etcd v0.5 cluster for the first time it can take a while
for all of the nodes to show up.

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
test/cluster: Update etcd configuration for v2.0

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
website: Update cluster bootstrap documentation with `flynn-host init`

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>