Maven integration

I recently wanted to try out the AutobahnAndroid library, but I found it regrettable that your library is not available in a Maven repository.

I see you have an issue open to add the library to the Sonatype OSS repository (issue 16), and on your mailing list I found a message that you are interested in doing so, but would like someone to Maven-ize the project ( https://groups.google.com/forum/?fromgroups=#!topicsearchin/autobahnws/maven/autobahnws/eOPf9LBxm14 ).

I made a pom file for the library, and I also Maven-ized the examples in the demo directory.

I hope this pull request can help you to get the library published on the Sonatype OSS repository (where things are already set up if I understand correctly: https://issues.sonatype.org/browse/OSSRH-4155 )