Rework crontab.
* Factor out two variables: MAILTO (email address for errors) and DEXONLINE_PATH (path to DEX installation).
* Remove all pipes and redirects. Cron jobs are normally quiet and any output automatically goes to MAILTO.
* Merge all the jobs into one file. They are now marked as "main site" and/or "mirror sites" and we can comment out the ones we don't need.
Closes #278.


git-svn-id: http://voronet.francu.com/repos/DEX@874 8d550267-2627-4c68-899f-85492a8dd5ca