CDK-95. Introduce cdk-morphlines-all maven artifact for ease of dependency management

Please consider this for inclusion. This basically gets us to follow Maven guidelines: http://books.sonatype.com/mvnref-book/reference/pom-relationships-sect-pom-best-practice.html and let the consumer project simply declare:

```
    <dependency>
      <groupId>com.cloudera.cdk</groupId>
      <artifactId>cdk-morphlines-all</artifactId>
      <version>${cdk.version}</version>
      <type>pom</type>
    </dependency>
```