Allow content-forests-per-host=0

[grtjn]

Would allow hooking up to an existing database with:

content-forests-per-host=0
content-db=some-other-db

It only needs replacement of xs:positiveInteger by xs:integer in setup.xqy (3 times).

Need to check wipe, but I thought that was safe too..

[grtjn]

In retrospect I don't think this makes sense. If someone wants to use an existing database as content-db, it is best to remove the section for the content-db from ml-config.xml entirely. It will prevent accidental creation, and changing of settings at bootstrap, and also prevent accidental removal at wipe.

[grtjn]

Created a wiki page for that: https://github.com/marklogic/roxy/wiki/Using-an-existing-Content-Database