Prepare for publising to Maven Central

* Inherit from org.sonatype.oss:oss-parent:7
* Add `sonatype-oss-release` in order to override plugin versions
  from parent pom
* Add `scm`, `issueManagement`, and `licenses`
* Add buildnumber-maven-plugin and enhanced configuration of the 
  maven-(jar|source|javadoc)-plugin to get proper build info into the 
  manifest.
Add license handling

LICENSE and NOTICE files are automatically created/updated during 
the build (maven-remote-resources-plugin). They are copied to the 
project root and are packaging in the META-INF folder in jar, 
source jar, and javadoc jar. A license header is automatically added 
to source files (license-maven-plugin).
Merge pull request #1 from unguiculus/mavencentral

Prepare for publising to Maven Central