jmhJar should not be up-to-date when jmsClasses change

Fix for https://github.com/melix/jmh-gradle-plugin/issues/10
Merge pull request #14 from chrisbrookes/master

jmhJar should not be up-to-date when jmsClasses change
Update README.adoc

Update plugin example version number to latest stable
Merge pull request #15 from epickrram/master

Update README.adoc
merge in upstream change
optionally use shadow jar plugin