Revise parameter handling for snippets

This version brings major improvements to handling parameters in snippets, thanks to amazing work by @michaelgwelch! It includes:

• Properly handle examples (#81)
• Support for "exploding" parameters that with arrays / objects (#83)
• Resolve $ref nodes for header parameters (#84)
• Properly lookup parameter values both at path and then at path.method for all types of parameters (#85)
• Added support for cookie parameters, label and matrix style path parameters, space and pipe delimited query parameters, resolving references in example schemas

All above cases are supported by a solid suite of tests. Thanks again, @michaelgwelch!!!

v0.13.0

• Increase httpsnippet version to 2.0.0 (#75, thanks to @restyler)

v0.12.1

• Fix bug when generating multipart/form-data requests (#73)

Thanks once more to @bpross for this contribution!

v0.12.0

• Adds support for query parameters defined on a path, not only on the method level (#71)
• Adds support generating snippets with multiple content-types (#72)

Huge thanks to @bpross for these two fantastic contributions!

Add x-www-form-urlencoded media type examples support

Add x-www-form-urlencoded media type examples support (#67). Thanks to @d-silva for this new feature!

v0.10.0

Adds support for using example field in parameter object #61 - Thanks to @cmullenx!

v0.9.3

• Support server overrides in paths / operations, thanks to @amitkgupta
• Bump dependencies to fix vulnerabilities
• Add Prettier for consistent code

v0.9.2

• Fix declaration of library as let to avoid TypeError - thanks @ZinoKader

v0.9.1

• Resolve $ref in body (addresses #49, thanks @rohit-gohri)
• Enable using placeholders in parameters defined per method (thanks @rohit-gohri)
• Address vulnerabilities

v0.9.0

• Fix error when using securityScheme of type oauth2 without scheme property (thanks @niteshhegde)
• Add example values to URL parameters when present (thanks @RolphH)