*: move away from python_rules

python_rules is completely broken when it comes to py2/py3 support.

Here, we replace it with native python rules from new Bazel versions [1] and rules_pip for PyPI dependencies [2].

rules_pip is somewhat little known and experimental, but it seems to work much better than what we had previously.

We also unpin rules_docker and fix .bazelrc to force Bazel into Python 2 mode - hopefully, this repo will now work
fine under operating systems where `python` is python2 (as the standard dictates).

[1] - https://docs.bazel.build/versions/master/be/python.html

[2] - https://github.com/apt-itude/rules_pip

Change-Id: Ibd969a4266db564bf86e9c96275deffb9610dd44
diff --git a/cluster/clustercfg/BUILD b/cluster/clustercfg/BUILD
index 5ada23c..28a776d 100644
--- a/cluster/clustercfg/BUILD
+++ b/cluster/clustercfg/BUILD
@@ -1,15 +1,13 @@
-load("@py_deps//:requirements.bzl", "requirement")
-
 py_binary(
     name = "clustercfg",
+    python_version = "PY3",
     srcs = [
         "clustercfg.py",
         "ca.py",
     ],
     visibility = ["//visibility:public"],
     deps = [
-        requirement("fabric"),
-        requirement("future"),
+        "@pip36//fabric",
         "//tools:secretstore_lib",
     ],
 )