Implement v2 of Swachalit API Layer

[abhisek]

Grape is integrated for exposing API. Check lib/api for example.

We need to complete the API for the following

Public

• [x] Authentication
• [x] Events
• [ ] Event Sessions
• [x] Chapters
• [ ] Event Registration

Lead

• [ ] Event mangement
• [ ] Venue management
• [ ] Chapter Management
• [ ] Mailers

[abhisek]

The auto-generated Swagger definition is available in staging:

https://swachalit.kubectl.in/api-v2/swagger