remove packaging tag to fallback to default type 'jar'
remove packaging tag to fallback to default type 'jar'

fixes #481

robertpanzer/asciidoctorj,abelsromero/asciidoctorj,abelsromero/asciidoctorj,abelsromero/asciidoctorj,lefou/asciidoctorj,lefou/asciidoctorj,robertpanzer/asciidoctorj,robertpanzer/asciidoctorj,asciidoctor/asciidoctorj,ysb33r/asciidoctorj,ysb33r/asciidoctorj,ysb33r/asciidoctorj,lefou/asciidoctorj,ysb33r/asciidoctorj,asciidoctor/asciidoctorj,lefou/asciidoctorj,asciidoctor/asciidoctorj