fixes pylint errors

examples/random_node.py

@@ -2,6 +2,7 @@
 
 __author__ = "Jarrod Pas <j.pas@usask.ca>"
 
+import sys
 from random import Random
 
 from pydtn import Network, Node, RandomTrace, RandomTraffic
@@ -62,4 +63,4 @@ def main():
 
 
 if __name__ == '__main__':
-    exit(main())
+    sys.exit(main())

examples/shed.py

@@ -99,4 +99,4 @@ def parse_args(args):
 
 
 if __name__ == '__main__':
-    exit(main(parse_args(sys.argv[1:])))
+    sys.exit(main(parse_args(sys.argv[1:])))