Adds README document
Adds description and repository fields to package.json
Adds async client dependency
BusinessHour model, Business#show page work, and refactors

- Refactors user & business model relationship to use Mongoose populations
- Adds slug field to business and new routing to reflect the new, more-readable URLs
- Moves state list and map styles into Angular constants and refactors existing uses
- Adds client admin route validation
- Adds tagLine field and 120-character length validation to Business
- View & style changes to reflect updates, including partial Business#show page