add rubocop gem, static code analyzer
add rubocop sample config file

.rubocop.yml and .rubocop_todo.yml
add .travis.yml
Merge branch 'rubocop' of github.com:gouf/shirasagi into gouf-rubocop
Merge branch 'gouf-rubocop'
fix: travis.yml
fix: public filter
fix public filter: request_method
fix category addon: @cur_node
fix: public routing