Use swagger parser to parse and validate swagger 2.0 spec

[subeeshcbabu-zz]

Use Swagger 2.0 parser and validator - https://github.com/BigstickCarpet/swagger-parser

We can use this module for these:

• Parses Swagger specs in JSON or YAML format
• Validates against the Swagger 2.0 schema and the Swagger 2.0 spec
• Resolves all $ref pointers, including external files and URLs
• Can bundle all your Swagger files into a single file that only has internal $ref pointers
• Can dereference all $ref pointers, giving you a normal JavaScript object that's easy to work with
• Configurable caching of external files and URLs

[subeeshcbabu-zz]

version 3.0.0 uses swagger-parser.