Defensive clause to cope with pList entries that do not contain a Messag...

...e element

The pList generated can contain dictionary entries that do not have a Message element:
```
		<dict>
			<key>LogType</key>
			<string>Default</string>
			<key>Timestamp</key>
			<date>2013-11-07T07:30:16Z</date>
			<key>Type</key>
			<integer>1</integer>
		</dict>
```

This small extra clause allows the script to deal with the scenario gracefully.

Signed-off-by: Richard Fisk <rfisk@seek.com.au>