Missing osgi headers (#288) and added support for Apache Karaf

[jmylly]

Fixing issue where org.simplejavamail.internal.* are not exported in Osgi.
In addition, have Apache Karaf feature available.

[bbottema]

Thank you for your effort. Question: is there a reason why you are using a nested a module named karaf-feaure? It deviated from how the other modules are configured in Maven.

[jmylly]

Thank you for your effort. Question: is there a reason why you are using a nested a module named karaf-feaure? It deviated from how the other modules are configured in Maven.

For the future development, we could have each module as separate, installable karaf feature, like

|-- karaf-module
|   |-- karaf-feature
|   |-- karaf-feature-auth-socks
|   |-- karaf-feature-dkim 
|   |-- karaf-feature-outlook
...

However, current PR doesn't have these submodules. I can also remove the submodule for now.

[bbottema]

Ahh, I see. Yes, let's remove the nested module structure until we have multiple modules to nest. You're welcome to perform the change, else I will do it later this week. Thanks.

[bbottema]

Released in 8.1.0

[bbottema]

Note, that for the next release, whenever that is, I'm renaming the module to karaf-module. Together with artifactGroup, that should be enough (as with the other modules).

So the dependency becomes org.simplejavamail:karaf-module:8.1.x