Adds pycrypto requirement and corrects server example in README

README.md

@@ -103,7 +103,7 @@ if __name__ == "__main__":
 Example server code:
 
 ```
-    from opcua import ua, Server
+    from opcua import ua, Server, ObjectIds
 
     server = Server()
     

setup.py

@@ -4,7 +4,7 @@ from distutils.command.install_data import install_data
 import sys
 
 if sys.version_info[0] < 3:
-    install_requires = ["enum34", "trollius", "futures"]
+    install_requires = ["enum34", "trollius", "futures", "pycrypto"
 else:
     install_requires = []