*: rejigger tls certs and more

This pretty large change does the following:

 - moves nix from bootstrap.hswaw.net to nix/
 - changes clustercfg to use cfssl and moves it to cluster/clustercfg
 - changes clustercfg to source information about target location of
   certs from nix
 - changes clustercfg to push nix config
 - changes tls certs to have more than one CA
 - recalculates all TLS certs
   (it keeps the old serviceaccoutns key, otherwise we end up with
   invalid serviceaccounts - the cert doesn't match, but who cares,
   it's not used anyway)
diff --git a/cluster/README b/cluster/README
index 034a28c..4eeb6b7 100644
--- a/cluster/README
+++ b/cluster/README
@@ -8,14 +8,14 @@
 
 There isn't yet a service for getting short-term user certificates. Instead, you'll have to get admin certificates:
 
-    clustercfg admincreds $(whoami)-admin
+    bazel run //cluster/clustercfg:clustercfg admincreds $(whoami)-admin
     kubectl get nodes
 
 Provisioning nodes
 ------------------
 
  - bring up a new node with nixos, running the configuration.nix from bootstrap (to be documented)
- - `clustercfg nodestrap bc01nXX.hswaw.net`
+ - `bazel run //cluster/clustercfg:clustercfg nodestrap bc01nXX.hswaw.net`
 
 That's it!