[web session] fix web session id bug on automatic reconnection. The web session id should keep the first connection id, then differ of the repo connection id once some reconnection has been done (since the session cookie isn't updated in such cases). Also, use a lock to avoid potential race condition on reconnection.

addressbook
basket
blog
book
calendar
comment
company
email
file
folder
i18ncontent
keyword
link
mailinglist
person
tag
timeseries
vcsfile