Change default value Distribution/Urgency in the changes file, when no CHANGES.txt is  provided

I provided a patch a default string "stable" was used for Distribution, "low" for the urgency even if i wrote in the control file with the following content

Distribution: snapshot
Urgency: high

here my jdeb maven configuration plugin

```xml
<configuration>
<deb>${project.build.directory}/debian/${project.name}_${project.version}${buildNumber}_all.deb</deb>
<changesOut>${project.build.directory}/debian/${project.name}_${project.version}${buildNumber}_all.changes</changesOut>
<verbose>true</verbose>
<controlDir>${project.build.directory}/control</controlDir>

...
</configuration>
```