add maven support

This patch adds a maven pom file which should set you up to publish artifacts to the maven central repo via Sonatype. 
Here is a link [to the process](https://docs.sonatype.org/display/Repository/Sonatype+OSS+Maven+Repository+Usage+Guide) for getting artifacts published.

It would be really helpful if there was a publicly released version of this library available via maven dependency management!