Added initial Gems

I separated production PG from development sql. in Addition, I added
the following gems

PG for deployment to heroku along with rails_12factor. rspec and
database cleaner for development.

#Seed data using FAKER
gem 'faker'
gem 'devise'
gem 'figaro'
gem 'pundit'
gem 'will_paginate', '~> 3.0.5'
added factory-girl