Fix edge case in coerce and add tests

This adds a baseline test case, as well as two tests (horizontal &
vertical) which failed prior to this change. I would encourage someone
to write more tests for the coerce goal functionality, but I am not
going to do it in this change :P

Change-Id: I76ee32cec46b9557fc5f5a09fa172be64b82cc70
diff --git a/frc971/control_loops/coerce_goal.cc b/frc971/control_loops/coerce_goal.cc
index 311d882..6fdc70f 100644
--- a/frc971/control_loops/coerce_goal.cc
+++ b/frc971/control_loops/coerce_goal.cc
@@ -1,11 +1,8 @@
 #include "frc971/control_loops/coerce_goal.h"
 
 #include "Eigen/Dense"
-
 #include "aos/controls/polytope.h"
 
 namespace frc971 {
-namespace control_loops {
-
-}  // namespace control_loops
+namespace control_loops {}  // namespace control_loops
 }  // namespace frc971