Parameter validation for the uuid format should not be case sensitive

[linelson]

Q	A
Bug or feature request?	Bug
Which Swagger/OpenAPI version?	2.0
Which Swagger-UI version?	3.4.4 (also looks like it impacts the current version)
How did you install Swagger-UI?	Built using npm run build, copied dist folder
Which browser & version?	Chrome 63.0.3239.132
Which operating system?	Windows 10

Demonstration API definition

Here's a sample parameter (modified from the petstore example swagger spec) with this issue:

                "parameters": [
                    {
                        "name": "petId",
                        "in": "path",
                        "description": "ID of pet to return",
                        "required": true,
                        "type": "string",
                        "format": "uuid"
                    }

Note that the parameter petId is of type string and and format uuid.
When a value of 78aea7e5-97c3-4e77-92ea-d40d6a3a4439 is entered in the swagger ui for parameter petId, the swagger ui works as expected. However, for 78AEA7E5-97C3-4E77-92EA-D40D6A3A4439, the same guid converted to upper case, the following occurs:

Expected Behavior

The value 78AEA7E5-97C3-4E77-92EA-D40D6A3A4439 is a valid uuid and so the swagger ui should accept it as the value for the petId parameter without producing an error.

Current Behavior

The following error is produced: "Value must be a Guid"

Possible Solution

In utils.js in the method validateGuid(val), set val = val.toLowerCase() before applying the case-sensitive regular expression (or modify the regex to be case insensitive).

Context

Users should be able to provide a valid guid as a value for a parameter with uuid format without first converting the guid to lower case.

[shockey]

@linelson, would you be able to open a PR for this?

[linelson]

I'll open a pr.