Switch to python3 and scipy from slycot

Turns out we need python3 matplotlib to make scipy work well enough to
place the poles correctly for our systems.  Rather than do it piecemeal,
do it all at once.

This includes a python opencv upgrade too to support the new python, and
a matplotlib upgrade.

Change-Id: Ic7517b5ebbfdca9cc90ae6a61d86b474f2f21b29
diff --git a/y2014_bot3/control_loops/python/drivetrain.py b/y2014_bot3/control_loops/python/drivetrain.py
index 48f2c9e..2990773 100755
--- a/y2014_bot3/control_loops/python/drivetrain.py
+++ b/y2014_bot3/control_loops/python/drivetrain.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 from __future__ import print_function
 from frc971.control_loops.python import drivetrain
diff --git a/y2014_bot3/control_loops/python/polydrivetrain.py b/y2014_bot3/control_loops/python/polydrivetrain.py
index d98e003..08e5583 100755
--- a/y2014_bot3/control_loops/python/polydrivetrain.py
+++ b/y2014_bot3/control_loops/python/polydrivetrain.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 import sys
 from y2014_bot3.control_loops.python import drivetrain
diff --git a/y2014_bot3/control_loops/python/polydrivetrain_test.py b/y2014_bot3/control_loops/python/polydrivetrain_test.py
index 434cdca..8e0176e 100755
--- a/y2014_bot3/control_loops/python/polydrivetrain_test.py
+++ b/y2014_bot3/control_loops/python/polydrivetrain_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 import polydrivetrain
 import numpy