Allow omitting version asterisk (e.g. allow HTTP 200 rather than just HTTP/* 200)

[jmoore34]

When the HTTP version is not important, it would be nice if you could write e.g. HTTP 200 instead of only HTTP/* 200 (i.e. supporting both syntaxes). In general, I think simple, intuitive syntax is one of Hurl's strengths, and I think supporting this would help further this goal, especially because it's similar to what you might see in a browser developer console.

[fabricereix]

I like it!
We could indeed remove the version check by simply removing fully the version part.

[fabricereix]

@jcamiel
for the grammar/AST, I would see the HTTP version as optional

response:
  lt*
  "HTTP" version? sp status lt
  header*
  response-section*
  body?

version:
    "/1.0"
  | "/1.1"
  | "/2"