[maven-release-plugin] copy for tag jruby-rack-1.2.2

[maven-release-plugin] copy for tag jruby-rack-1.2.1

[maven-release-plugin] copy for tag jruby-rack-1.2.0

[build] disable javadoc lint on Java 8

prepare for 1.1.21

prepare for 1.1.20

prepare for 1.1.19

prepare for 1.1.18

update pom to generate sources/javadoc and sign + prepare for release…

… 1.1.17

prepare for 1.1.16