Create an attribute to define the crontab user

Update the default crontab user to be a configurable attribute
with the default value being apache.
Use cron_d instead of executing crontab

This will prevent exiting cron entries from being broken in the process of
updating to the new functionality. This is also a better way of working.
Remove deprecated file
Restore the conifgurable minute into the recipe
Apply version constraint that will allow only patch updates
Merge pull request #68 from inviqa/features/crontab-security

Implement a more secure crontab default setup