release jfreesane 1.0, move to bintray plugin 1.8.4

The bintray plugin update was required to fix
bintray/gradle-bintray-plugin#291.

update release docs

update release version

use correct group identifier

[maven-release-plugin] copy for tag jfreesane-0.95

[maven-release-plugin] copy for tag jfreesane-0.94

[maven-release-plugin] copy for tag jfreesane-0.93

[maven-release-plugin] copy for tag jfreesane-0.92

[maven-release-plugin] copy for tag jfreesane-0.91

try to get maven-release-plugin working with github