Re-order matplotlib.use() calls (before plt import)

Addressing warning:

This call to matplotlib.use() has no effect because the backend has
already been chosen; matplotlib.use() must be called *before* pylab,
matplotlib.pyplot, or matplotlib.backends is imported for the first
time.

Author: felker

plasma/models/runner.py

@@ -10,9 +10,9 @@
 from hyperopt import hp, STATUS_OK
 import numpy as np
 import sys
-import matplotlib.pyplot as plt
 import matplotlib
 matplotlib.use('Agg')
+import matplotlib.pyplot as plt
 
 # if sys.version_info[0] < 3:
 #     from itertools import imap

plasma/models/shallow_runner.py

@@ -20,9 +20,9 @@
 import datetime
 import time
 import numpy as np
-# import matplotlib.pyplot as plt
 import matplotlib
 matplotlib.use('Agg')
+# import matplotlib.pyplot as plt
 
 # import sys
 # if sys.version_info[0] < 3:

plasma/utils/performance.py

@@ -5,10 +5,10 @@
 import numpy as np
 from pprint import pprint
 import os
-import matplotlib.pyplot as plt
-from matplotlib import rc
 import matplotlib
 matplotlib.use('Agg')  # for machines that don't have a display
+import matplotlib.pyplot as plt
+from matplotlib import rc
 rc('font', **{'family': 'serif', 'sans-serif': ['Times']})
 rc('text', usetex=True)