upgrade JRuby and JRuby plugin

- upgrade JRuby to 1.7.17
- upgrade JRuby plugin to 0.1.10
- tweak Gradle build to allow tests to be run on JDK6
- reenable openjdk6 in build matrix
Merge pull request #241 from mojavelinux/jruby-upgrade

upgrade JRuby and JRuby plugin
add config file for appveyor
Merge pull request #245 from mojavelinux/appveyor-config

add config file for appveyor
show test results in console output when info is enabled

- show test results in console when info is enabled
- add JDK 1.7.0 to build matrix on AppVeyor
- set TERM=dumb when running builds on AppVeyor
update AppVeyor config
set PATH correctly in AppVeyor config
tidy up build scripts

- separate out common logic for distribution and non-distribution builds
- move library versions to top-level ext block
- enable sources & javadoc for all jar archives