Because we changed search backends from PyLucene to Haystack, users need to

change their crontabs to use the new indexing commands. This change makes it so

that we replace the example crontab in the site directory with the templated

version on upgrade.
Some changes had to be made to template processing to avoid making assumptions

about some of the data, since upgrade doesn't ask any questions about domain

name, site root, etc. These aren't required for the cron template, so it all

works OK.

Created a 1.7.x site directory and saw that the sample crontab listed our old

PyLucene-based indexing commands. Ran 'rb-site upgrade' with this code and saw

it replaced with the new Haystack management commands.