Move 2015-specific code to its own folder.

Known issues:
  -I didn't change the namespace for it, but I am open to discussion
   on doing that in a separate change.
  -There are a couple of files which should get split out into
   year-specific and not-year-specific files to reduce how much needs
   to get copied around each year still.
  -The control loop python code doesn't yet generate code with the
   right #include etc paths.

Change-Id: Iabf078e75107c283247f58a5ffceb4dbd6a0815f
diff --git a/frc971/zeroing/zeroing.h b/frc971/zeroing/zeroing.h
index 08911ac..4176f48 100644
--- a/frc971/zeroing/zeroing.h
+++ b/frc971/zeroing/zeroing.h
@@ -23,7 +23,7 @@
 // the pot and the indices.
 class ZeroingEstimator {
  public:
-  ZeroingEstimator(const constants::Values::ZeroingConstants &constants);
+  ZeroingEstimator(const constants::ZeroingConstants &constants);
 
   // Update the internal logic with the next sensor values.
   void UpdateEstimate(const PotAndIndexPosition &info);