Add priority queue container to AOS.

Needed in order to handle out-of-order incoming EKF observations.

Also, rename ring_buffer folder to more generic containers/ and
buildify y2017/BUILD.

Change-Id: Idc343729628e24eceb024b80a2439170ead289de
diff --git a/aos/containers/BUILD b/aos/containers/BUILD
new file mode 100644
index 0000000..ff0b600
--- /dev/null
+++ b/aos/containers/BUILD
@@ -0,0 +1,37 @@
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "ring_buffer",
+    hdrs = [
+        "ring_buffer.h",
+    ],
+)
+
+cc_test(
+    name = "ring_buffer_test",
+    srcs = [
+        "ring_buffer_test.cc",
+    ],
+    deps = [
+        ":ring_buffer",
+        "//aos/testing:googletest",
+    ],
+)
+
+cc_library(
+    name = "priority_queue",
+    hdrs = [
+        "priority_queue.h",
+    ],
+)
+
+cc_test(
+    name = "priority_queue_test",
+    srcs = [
+        "priority_queue_test.cc",
+    ],
+    deps = [
+        ":priority_queue",
+        "//aos/testing:googletest",
+    ],
+)