*: 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/tools/BUILD b/tools/BUILD
index cd4642a..2be1cea 100644
--- a/tools/BUILD
+++ b/tools/BUILD
@@ -2,8 +2,8 @@
 load("@py_deps//:requirements.bzl", "requirement")
 load("//bzl:rules.bzl", "copy_go_binary")
 
-py_binary(
-    name = "secretstore",
+py_library(
+    name = "secretstore_lib",
     srcs = ["secretstore.py"],
     visibility = ["//visibility:public"],
     deps = [
@@ -12,11 +12,10 @@
 )
 
 py_binary(
-    name = "clustercfg",
-    srcs = ["clustercfg.py"],
+    name = "secretstore",
+    srcs = ["secretstore.py"],
     visibility = ["//visibility:public"],
     deps = [
-        requirement("fabric"),
         requirement("future"),
     ],
 )