[MJAR-267] Propertize addDefaultImplementationEntries and addDefaultSpecificationEntries

**[Peter Rader](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=grim)** opened **[MJAR-267](https://issues.apache.org/jira/browse/MJAR-267?redirect=false)** and commented

The version-entries of MANIFEST.MF are important requirements to a couple of frameworks (eclipse, felix, liferay) and specifications (portlets, osgi) in order to load those modules in an consistent way.

At the moment this deal-breaking configuration of the project is essential in order to create an valid portlet / osgi-modul. Without having the boolean-values as properties we encounter three downsides:
1. Only using an indispensable dirty mid-size overhead of overriding the MJAR's modul-configuration we can force MJAR to create this essential MANIFEST.MF-entries.
2. We are unable to early fail the build on missing MANIFEST.MF-version-entries. Even more worse the build will generate invalid osgi/portlets quitting "successfully".
3. A CI server like Hudson or Jenkins is not able to flange the MANIFEST.MF-version-entries hindsightly.

Suggestion:

Be able to direct the generation of version informations like this:

> `mvn clean install -Dmaven.addDefaultImplementationEntries=true -Dmaven.addDefaultSpecificationEntries=true`

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This issue is a sub-task of [MJAR-57](https://issues.apache.org/jira/browse/MJAR-57)

Start from the plugin entry points for addDefaultImplementationEntries and addDefaultSpecificationEntries and trace how they control MANIFEST.MF version entries. Use the Maven command shown in the issue to verify both properties can be enabled, and confirm the resulting manifest contains the requested version information.

Written by the indexing model from the issue text.