pythonPackages.tlslite: delete, migrate refs to pythonPackages.tlslite-ng

tlslite has a test failure on Python 3.7 [0]. @tomato42, a commiter of
tlslite and author of tlslite-ng said, that tlslite is abandoned (last
commit 2015) and tlslite-ng should be used as a drop in replacement.

[0] https://github.com/trevp/tlslite/issues/121

pkgs/development/python-modules/tlslite/default.nix

@@ -1,21 +0,0 @@
-{ stdenv
-, buildPythonPackage
-, fetchPypi
-}:
-
-buildPythonPackage rec {
-  pname = "tlslite";
-  version = "0.4.8";
-
-  src = fetchPypi {
-    inherit pname version;
-    sha256 = "1fxx6d3nw5r1hqna1h2jvqhcygn9fyshlm0gh3gp0b1ji824gd6r";
-  };
-
-  meta = with stdenv.lib; {
-    description = "A pure Python implementation of SSL and TLS";
-    homepage = https://pypi.python.org/pypi/tlslite;
-    license = licenses.bsd3;
-  };
-
-}