added and recategorized gem into default, development and test group
added and recategorized gem into default, development and test group

rspec gem was moved to default group
rails_12factor gem and puma gem were added to production group
shotgun gem was moved to development and test group

All these changes are designed to fulfill Heroku production requirement.

Signed-off-by: Holloway, Kean Ho <bbd8faa40b0f348214bf4124b281a301299ba6dd@gmail.com>

garywong79/ibilik,lirenyeo/cut-url-sinatra,alxh87/quora-clone,garywong79/mudah.my,alxh87/quora-clone,hollowaykeanho/quora-clone-demo,hollowaykeanho/ibilik-accessment,garywong79/mudah.my,NextAcademy/quora-clone,junster90/shorty,bsjt10/ibilik-accessment,jylee91/ibilik-accessment,dvdhoek/quora-clone,ianng89/quora-clone,dvdhoek/bitly-clone,garywong79/w4d1-buildingourfirstwebapp,hollowaykeanho/ibilik-accessment,dvdhoek/bitly-clone,iamatee/quora_website,junster90/shorty,lirenyeo/cut-url-sinatra,garywong79/w4d2-html-css,jylee91/ibilik-accessment,NaMusS/mini_quora,ianng89/quora-clone,macintorch/bitly-clone,jloo87/RR_2_Javascript,TerryQu3k/BitlyClone,garywong79/w4d4-jazzingitupwithJquery,hollowaykeanho/sinatra-web-server,garywong79/w4d5-production_readiness,macintorch/bitly-clone,iamatee/quora_website,dvdhoek/quora-clone,garywong79/ibilik,hollowaykeanho/craigslist,TerryQu3k/BitlyClone,anyatan/bitly-clone,hollowaykeanho/quora-clone-demo,syahmiibrahim/sinatra-web-server,WilliamYap3/sinatra-craigslist,garywong79/w4d4-asynchonousform,alxh87/quora-clone,garywong79/w4d5-production_readiness,yowchun93/Sinatra_flashcards_v2,hollowaykeanho/craigslist,garywong79/w4d4-asynchonousform,hollowaykeanho/sinatra-web-server,dvdhoek/bitly-clone,hollowaykeanho/airbnb-accessment,anyatan/bitly-clone,benjaminyeo/sinatra_bnb,NaMusS/mini_quora,jloo87/RR_2_Javascript,macintorch/bitly-clone,jylee91/ibilik-accessment,ianng89/quora-clone,NextAcademy/quora-clone,garywong79/w4d4-jazzingitupwithJquery,lirenyeo/cut-url-sinatra,yowchun93/Sinatra_flashcards_v2,hollowaykeanho/craigslist,benjaminyeo/sinatra-craiglist,junster90/shorty,WilliamYap3/sinatra-craigslist,garywong79/w4d2-html-css,garywong79/w4d1-extendingshorturl,hollowaykeanho/airbnb-accessment,garywong79/w4d1-buildingourfirstwebapp,syahmiibrahim/sinatra-web-server,iamatee/quora_website,garywong79/w4d1-extendingshorturl,benjaminyeo/sinatra_bnb,anyatan/bitly-clone,dvdhoek/quora-clone,bsjt10/ibilik-accessment,benjaminyeo/sinatra-craiglist