TST: move scipy import in create_dat.py into main() to avoid test failures on Travis (scipy is not a dependency of pywt)

Author: grlee77

pywt/data/create_dat.py

@@ -18,10 +18,11 @@
 import sys
 
 import numpy as np
-from scipy.misc import imread
 
 
 def main():
+    from scipy.misc import imread
+
     if len(sys.argv) != 3:
         print(__doc__)
         exit()