[FIX] document_ftp/document_webdav: correctly fix what was incorrectly fixed in

[FIX] document_ftp/document_webdav: correctly fix what was incorrectly fixed in
revno 4821, revision-id tfr@openerp.com-20110628141309-oag99snygj3vuqwn :
pooler.get_db_only was removed from the server but not from the addons.
It seems the commit 4821 tried to solved the situation by using get_db
instead, which is wrong and it will load the db instead of just trying
to get a cursor. This commit solves correctly the removel of get_db_only:
by using sql_db.db_connect (for which get_db_only was an alias).

bzr revid: vmt@openerp.com-20110909113916-td9o8yct0u5bitb6