Update conwaylife.py

Import statements have been moved to the top of the file.

examples/conwaylife.py

+#import essential libraries
+import lcd
+import pyb
+
 # do 1 iteration of Conway's Game of Life
 def conway_step():
     for x in range(128):        # loop over x coordinates
@@ -37,8 +41,6 @@ def conway_go(num_frames):
         pyb.delay(300)
 
 # PC testing
-import lcd
-import pyb
 lcd = lcd.LCD(128, 32)
 conway_rand()
 conway_go(1000)