Add skip configuration paramter

Add support for a skip parameter similar to deploy-plugin. In a multi-module project the parent module, which would be <packaging>pom</packaging>, does not need to be deployed. Another use case for us is when we only want to deploy a few artifacts for testing.

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-deploy-plugin</artifactId>
<configuration>
<skip>$

</skip>
<altDeploymentRepository>$

</altDeploymentRepository>
</configuration>
</plugin>