builtin.Authenticate panics if the Authorization header is missing or empty

[mansam]

// Authenticate the token
func (r *Builtin) Authenticate(request *Request) (jwToken *jwt.Token, err error) {
	token := strings.Replace(request.Token, "Bearer", "", 1)
	token = strings.Fields(token)[0]

If the Authorization header is missing or the string after replacement is nothing but whitespace, then strings.Fields will return an empty slice, and the attempt to index into it will panic. This should be fixed to return an auth failure.

[konveyor-ci-bot]

This issue has been marked 'good first issue'
Please, make sure it aligns with the criteria found here

[jortel]

I do not think changes to the AUTH layer is a good first issue.