Import Python jinja2 for working with templates

This provides a framework for dealing with templates. A bit overkill for
what I need to do, but convenient to have around.

Change-Id: I0554a5df120624f36c536655e0578754273555b9
diff --git a/build_tests/BUILD b/build_tests/BUILD
index 28dc677..e837390 100644
--- a/build_tests/BUILD
+++ b/build_tests/BUILD
@@ -124,3 +124,10 @@
     srcs_version = "PY2AND3",
     deps = ["@opencv_contrib_nonfree_amd64//:python_opencv"],
 )
+
+py_test(
+    name = "python_jinja2",
+    srcs = ["python_jinja2.py"],
+    srcs_version = "PY2AND3",
+    deps = ["@python_jinja2"],
+)