[FIXED JENKINS-11073] handle failure to set timestamp on Windows platforms more gracefully - this time hopefully for real

"-version" option.

- make AccountInfo a separate describable to help the UI
- added help file explaining why one might want to do this.

When using HTTP full duplex connections the upstream channel can be idle for
long periods of time and the webserver will time the connection out. Jenkins
sees this and terminates the downstream channel causing the unexpected closure
of the read channel in the CLI client.

Timeout of 15 seconds is based on the 20 second default timeout as seen in
Ubuntu Oneiric Tomcat 6 installations.

eagerly.

It would be better to find out why the nextBuildNumber is at times empty.
In the mean time this will find the appropriate number and write it to the file.

This lets us get rid of Xalan safely (as well as other often problematic
dependencies like nekohtml + Xerces combo), and reduce the dependency
footprint.