Added Path object to represent a path for the arm to follow.

Change-Id: Ib16a968dacbdc23517a9057f94c4c4c11d6bbdc2
diff --git a/y2018/control_loops/superstructure/arm/BUILD b/y2018/control_loops/superstructure/arm/BUILD
new file mode 100644
index 0000000..2862a6a
--- /dev/null
+++ b/y2018/control_loops/superstructure/arm/BUILD
@@ -0,0 +1,22 @@
+cc_library(
+    name = "trajectory",
+    srcs = [
+        "trajectory.cc",
+    ],
+    hdrs = [
+        "trajectory.h",
+    ],
+    deps = ["//third_party/eigen"],
+)
+
+cc_test(
+    name = "trajectory_test",
+    srcs = [
+        "trajectory_test.cc",
+    ],
+    deps = [
+        ":trajectory",
+        "//aos/testing:googletest",
+        "//third_party/eigen",
+    ],
+)