update debian/ for new seafile-client
update windows build script for client 2.0
[deb] update deb version to 2.0.1
[client] update msi/deb version to 2.0.2
[client] upgrade msi/deb version to 2.0.3
[client] update msi/deb version to 2.0.4
fixed a bug in 2.0 upgrade script
[scripts] update build-msi.py
[server] Fix a few problems for using external storage.

* Ignore fsync() error if the file system doesn't support it;
* Don't create or load config.db and chunkserver.db.
Merge branch '2.0'
Merge branch '2.0-client'