[client] Update index after syncing with existing folder.
[client] Improve clone procedure.

* Don't checkout/merge if remote root is empty.
* Delete repo information in db before clone, if the repo was corrupt.
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
Modify readme
[scripts] update build-msi.py
[scripts] fixed a typo in setup-seafile-mysql.py
[server] Improve MySQL db config.

* Allow password with special characters;
* Accept port configuration;
* Allow using ssl connection.

Example:
[database]
type = mysql
host = 127.0.0.1
port = 3306
user = seafile
password = P@$$word
db_name = seafile-db
use_ssl = True
[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'