Updated to use absolute imports

I used to add .\code to the path, which was an absurd hack.
Now all code is imported with import code.foo.

code/gh_internal.py

@@ -16,18 +16,14 @@ for more information.
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import sys
-sys.path.insert(0, '..')
-import book_plots
+
+import code.book_plots as book_plots
 import numpy as np
 from matplotlib.patches import Circle, Rectangle, Polygon, Arrow, FancyArrow
 import pylab as plt
 import time
 
 
-
-
-
 def plot_gh_results(weights, estimates, predictions, time_step=0):
 
     n = len(weights)