Feature/basic app setup

This PR is to get setup nicely to make us productive before coding up the models, service classes etc

- README file with setup instructions
- Rspec setup for tests
- Rubocop setup
- Pry setup for debugging
- Foreman and unicorn setup
- Simplecov, VCR, webmock, fabrication, faker etc for tests

Also, added the models to this PR for
- User
- City
- Subscription
- Weather Reading

Also added the 
- Reporting service class for sending email
- Mailer to send out emails
- Sidekiq setup
- Worker to initiate the sending of email

Also added the service class for fetching data from open weather map API, parsing it and storing it in the database