Change setup.py the default install without cpp implementation. Otherwise, python release will have some problem


git-svn-id: http://protobuf.googlecode.com/svn@603 630680e5-0e50-0410-840e-4b1c322b438d
merge 2.6.0 to trunk


git-svn-id: http://protobuf.googlecode.com/svn@604 630680e5-0e50-0410-840e-4b1c322b438d
update zip and tar for 2.6.0


git-svn-id: http://protobuf.googlecode.com/svn@605 630680e5-0e50-0410-840e-4b1c322b438d