Remove use of built-in new_http_archive in WORKSPACE file

WORKSPACE

@@ -1,3 +1,5 @@
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
 new_git_repository(
     name = "googletest",
     build_file = "gmock.BUILD",
@@ -5,11 +7,11 @@ new_git_repository(
     tag = "release-1.8.0",
 )
 
-new_http_archive(
+http_archive(
     name = "six_archive",
-    build_file = "six.BUILD",
+    build_file = "@//:six.BUILD",
     sha256 = "105f8d68616f8248e24bf0e9372ef04d3cc10104f1980f54d57b2ce73a5ad56a",
-    url = "https://pypi.python.org/packages/source/s/six/six-1.10.0.tar.gz#md5=34eed507548117b2ab523ab14b2f8b55",
+    urls = ["https://pypi.python.org/packages/source/s/six/six-1.10.0.tar.gz#md5=34eed507548117b2ab523ab14b2f8b55"],
 )
 
 bind(