Warning, could not find a line that matches the pattern '(Class|Interface|Enum)'. Class diagram reference not inserted

Hi,

Nice tool!

But when I execute this in maven project on Travis, I always have this issues during the generation of the javadoc :

```
Warning, could not find a line that matches the pattern '(Class|Interface|Enum) Gpio.*'.
Class diagram reference not inserted
```

See the build #135 in me repository : https://travis-ci.org/ericpinet/ConnectLife

I setup the UMLGraph with maven like this:

```


org.apache.maven.plugins
maven-javadoc-plugin
2.10.3

com.connectlife.test
org.umlgraph.doclet.UmlGraphDoc

org.umlgraph
doclet
5.1

-all -view -views
true


```

Why the pattern is not match? The javadoc plugin version isn't compatible with this doclet?