Update ChangeLog and version files for 0.20.2

ChangeLog

+2016-11-10, v0.20.2
+	* Fix a bug where the disk was truncated to the size of the image file
+	  if the used disk template was "file" or "sharedfile"
+	* Make image copying work when using userspace disk URIs
+
 2016-10-4, v0.20.1
 	* Fix a "no properly formatted MD5 checksum lines found" bug in
-          snf-image-update-helper
+	  snf-image-update-helper
 
 2016-10-3, v0.20
 	* Add support for NetworkManager in CofigureNetwork configuration task

docs/version.py

-__version__ = "0.20.2.dev0"
+__version__ = "0.20.2"

version.m4

-m4_define([devflow_version], [0.20.2.dev0])
+m4_define([devflow_version], [0.20.2])