Feature split ruby rpm

toplevel-Makefile
* move gem packages installation with bundle command to rpmbuild/rules

rrpmbuild/rules
* integrate `vendor/bundle/ruby` directories
  - dcmgr
  - frontend/admin
  - frontend/dcmgr_gui
  - dolphin

wakame-vdc.spec
* exclude cached gem files
* require wakame-vdc-ruby
* define wakame-vdc-ruby version range