Change version to 2.0.0

Author: mfripp

switch_model/version.py

@@ -2,8 +2,8 @@
 # Licensed under the Apache License, Version 2.0, which is in the LICENSE file.
 """
 This file should only include the version. Do not import any packages or
-modules in here because this file needs to be executed before SWITCH is
+modules here because this file needs to be executed before SWITCH is
 installed and executed in environments that don't have any dependencies
 installed.
 """
-__version__='2.0.0b4'
+__version__='2.0.0'