Bug#752547: Broken symlink to solr's webapp

[Emmanuel Bourg]

There is still an issue in sid, the deployment no longer works after the
update to jetty8 in solr-jetty/3.6.2+dfsg-4. There are two reasons to this:

1. the symlink to the web app is misplaced (/var/lib/jetty should have
been updated to /var/lib/jetty8)

2. Jetty no longer follows symbolic links in its webapp directory. The
link has to be replaced with a context descriptor installed under
/etc/jetty8/contexts