Modified crontab installation to be more efficient

Previously, installing a crontab used meant writing the old config to a file on disk, writing to the end of that file, telling cron to use that file as the new crontab, then deleting all the temporarily created files/folder.

Now it reads the old crontab into a variable, modifies that variable, then installs the new crontab by feeding into the stdin of `crontab`. It's much shorter and cleaner, and results in less disk IO.
Fixed bug which always sent email.

There was a mistake in the previous version such that even if no new posts had been made, it would still send an email. This resulted in waaaaay to many emails.

Additionally, switched the files from space-based indentation to tab-based indentation.
Moved from spaces to tabs.
Merge pull request #6 from lelandbatey/master

Modified crontab installation to be more efficient