Fix OpenAPI 2 generator to produces vallid OpenAPI 2

[danieltheodosius]

Changes:

• rename #/components/schemas/... into #/definitions/...
• remove requestBody and replace it with body parameters
• append requestContentType as consumes attribute

Before change:

      parameters: []
      requestBody:
        $ref: '#/components/schemas/CreateUserRequest'
      responses:
        '200':
          schema:
            $ref: '#/components/schemas/CreateUserResponse'
          description: ''
        default:
          description: ''

After the change:

      consumes:
        - application/json
      parameters:
        - in: body
          name: body
          description: TODO
          required: true
          schema:
            $ref: '#/definitions/CreateUserRequest'
      responses:
        '200':
          schema:
            $ref: '#/definitions/CreateUserResponse'
          description: ''
        default:
          description: ''