[web] allow configuration of the Content-disposition value
The `set_content_type` function now takes and optional `disposition` parameter
to control the value of this HTTP header.
Use of `Content-disposition: inline` with a filename parameter are valid, so
the presence of filename does not allows to choose between `attachment` and
`inline`
change_attribute_type('CWCache', 'timestamp', 'TZDatetime')
change_attribute_type('CWUser', 'last_login_time', 'TZDatetime')
change_attribute_type('CWSource', 'latest_retrieval', 'TZDatetime')
drop_attribute('CWSource', 'synchronizing')
add_attribute('CWSource', 'in_synchronization')