Reformat message insert error message to make it more readable in stdout

If a message can`t be inserted to the database a message will appear:

```
...
ERROR: Runtime error while trying to write
                message with message-id '<mailman.1064903287.11967.typo3-dev@lists.netfielders.de>'. That message has not been written
                to the database, but the execution has not been stopped. Please
                report this failure including the message-id and the URL for
                the mbox.
...
```

This message looks a little bit "disformatted" at the console.
With this pull request the error message will look like 
```
...
Already downloaded http://lists.typo3.org/pipermail/typo3-dev/2014-February.txt.gz
Already downloaded http://lists.typo3.org/pipermail/typo3-dev/2014-March.txt.gz
Already downloaded http://lists.typo3.org/pipermail/typo3-dev/2014-April.txt.gz
Already downloaded http://lists.typo3.org/pipermail/typo3-dev/2014-May.txt.gz
Found substring 2014-June in URL http://lists.typo3.org/pipermail/typo3-dev/2014-June.txt.gz...
Retrieving http://lists.typo3.org/pipermail/typo3-dev/2014-June.txt.gz...
Already analyzed http://lists.typo3.org/pipermail/typo3-dev/2003-February.txt.gz
Already analyzed http://lists.typo3.org/pipermail/typo3-dev/2003-June.txt.gz
Already analyzed http://lists.typo3.org/pipermail/typo3-dev/2003-July.txt.gz
Analyzing /home/vagrant/.mlstats/compressed/lists.typo3.org/pipermail/typo3-dev/2003-August.txt.gz
ERROR: Runtime error while trying to write message with message-id '<mailman.1059780227.5619.typo3-dev@lists.netfielders.de>'.
That message has not been written to the database, but the execution has not been stopped.
Please report this failure including the message-id and the URL for the mbox.
ERROR: Runtime error while trying to write message with message-id '<mailman.1059773096.31701.typo3-dev@lists.netfielders.de>'.
That message has not been written to the database, but the execution has not been stopped.
Please report this failure including the message-id and the URL for the mbox.
ERROR: Runtime error while trying to write message with message-id '<mailman.1059813362.15620.typo3-dev@lists.netfielders.de>'.
That message has not been written to the database, but the execution has not been stopped.
Please report this failure including the message-id and the URL for the mbox.
...
```