Cronjob to send customer a daily report via email

Timesheet items from the *previous day* will be used.
If time spans reach the next day, the last entry will be cut off at midnight and the rest will be included in the following day.
Setup the cron like this:
5 0 * * * /path/to/php /absolute/path/to/kimai/shellscripts/cron.php
this will run 0:05 every day.
For the cronjob to work, it must be activated for the customer and an email address must be set. Also the system administrator email address should be set. This will be the sender address.

TODO:
* make email subject configureable via admin panel

IDEAS:
* cronjob extension
* weekly reports
* monthly reports
* Pivot (#314)

I changed a lot of whitespace, to see the real diff, add ?w=1 to the url.
Do you plan on implementing plain text for this mail? Maybe just add a second template file which generates plain text instead of HTML.