Mavenize the library, issue dustismo/TrendrrBeanstalk#18

Notes:
* removed `lib` from the sources, this is a dependency and managed by Maven
* `MANIFEST.MF` is generated mostly as it was via `build.xml`, but timestamp format will be different
* release process is managed by Maven "release" plugin. The typical scenario: http://maven.apache.org/maven-release/maven-release-plugin/usage.html
* I've made an assumption that releases go to Sonatype OSS repository.