dc/topo: unvendor viz.js

This instead grabs a prebuild viz.js 2.x from a GH release.

Ideally we would use some more generic JS dep mechanism here (there's
some Good (tm) ones for Bazel now!), but this will do for now.

Change-Id: I58e9f67534acd2e3d08d93dc5f9a989dbbbbe3d1
Reviewed-on: https://gerrit.hackerspace.pl/c/hscloud/+/1721
Reviewed-by: radex <radex@hackerspace.pl>
diff --git a/WORKSPACE b/WORKSPACE
index 974c4aa..27cba12 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -293,3 +293,7 @@
     sha256 = "f49e9e8d25108f7f22d5a51c756b2fe40cbe36347ad297e31a767376172f2845",
     urls = ["https://github.com/projectcalico/calicoctl/releases/download/v3.15.5/calicoctl"],
 )
+
+# viz.js 2.x used by //dc/topo
+load("//third_party:vizjs.bzl", "vizjs_repositories")
+vizjs_repositories()