Release 0.7.0

Release 0.7.0

• client.server_version now is aliase to
  client.services.db.server_base_version
• Added services.db.server_base_version() which could be safely compared like:
  client.services.db.server_base_version() >= pkg_resources.parse_version('9.0')
• Added method search_read to orm.object
• Drop support of OpenERP 6.0
• ext.repr: Added ability to pass table format to .as_table method
  tablefmt arg must be suitable for tabulate.tabulate method from
  Tabulate package
• Added openerp_proxy.experimental subpackage.
• Refactored session logic. Logic related to database / client connection
  management moved to separate class openerp_proxy.session.ClientManager
  which can be used outside session logic.
• Added Client.ref method, then returns Record instance for
  specified xmlid
• Added Client.database_version_full and Client.database_version
  properties
• Added Session.del_db and ClientManager.del_client methods
• Added client.services.db.db_exist method wrapper