Timeline view of a build

Hi,

I implemented a new feature for your plugin which export a view of the maven build as a html page. This feature is really interresting for longs builds, it permits to see the theirs parallelism degree. 

This feature is useless for shorts build, but we schedule a next step which is to customize the scale value for the time axe. There is also an highlight system for dependencies implemented in the HTML page, but datas are not filled yet.

This feature can be activated by using this profile :
```xml
<profile>
   <id>timeline</id>
   <properties>
      <maven-build-utils.activate-timeline>true</maven-build-utils.activate-timeline>
   </properties>
</profile>
```

When the build is done, you can reach the picture with 
```bash
iceweasel timeline.html
```

Thanks !