Create swagger specs and implement swagger UI

[encX]

Blocked by #14

Initial swagger specs

swagger: "2.0"
info:
  description: ""
  version: "1.0.0"
  title: "Bangkok Transit Planner API"
schemes:
- "https"
- "http"
paths:
  /stations:
    get:
      summary: Get all stations list
      produces:
        - application/json
      responses:
        200:
          description: Get success
          schema:
            type: array
            items:
              $ref: "#/definitions/station"
        500:
          description: Server error
  /routes:
    get:
      summary: Get all possible routes from station A to station B
      produces:
        - application/json
      parameters:
        - name: from
          in: query
          description: Starting station ID
          type: number
          format: int
          required: true
        - name: to
          in: query
          description: Ending station ID
          type: number
          format: int
          required: true
      responses:
        200:
          description: Get success
          schema:
            type: array
            items:
              $ref: "#/definitions/route"
        500:
          description: Server error
  
definitions:
  station:
    type: object
    properties:
      name:
        type: string
      id:
        type: number
        format: int

  route:
    type: object
    properties:
      cost:
        type: number
      stations:
        type: array
        items:
          $ref: "#/definitions/station"

https://editor.swagger.io/