Develop

[samuelralak]

CHANGELOG
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- created a staging server at https://bubewa-staging.herokuapp.com/
- added full text search (basic)
- moved average rating calculation to controller - calculated when user submits a review. 
- rake task to  calculate average rating for existing data - `bundle exec rake reviews:update_average`
- removed turbolinks for the greater good
- added categories seed data
- created rake task to populate users - `bundle exec rake populate:users`
- moved 'aws_region' to an ENV variable
- search engine optimization for the single listing page
- set max height to thumbnail images

[samuelralak]

@gichuru you may need to run heroku run rake reviews:update_average after pushing the changes to Heroku or bundle exec rake reviews:update_average on your local/development environment. Kindly review the rest of the changes and let me know your thoughts.