Add travis-ci with ruby 2.2.0

Signed-off-by: Youhei SASAKI <uwabami@gfd-dennou.org>
Add travis-ci with ruby-head, jruby-head

Signed-off-by: Youhei SASAKI <uwabami@gfd-dennou.org>
Update dependencies, Add test-unit

Signed-off-by: Youhei SASAKI <uwabami@gfd-dennou.org>
Update travis.yml: Drop mruby-*

Signed-off-by: Youhei SASAKI <uwabami@gfd-dennou.org>
Update travis.yml: Drop jruby-head

Signed-off-by: Youhei SASAKI <uwabami@gfd-dennou.org>