Net::HTTP.get_response can receive URI as string

[kyanagi]

We need to pass a URI object to Net::HTTP.get_response (or Net::HTTP.get).

Net::HTTP.get_response(URI('http://www.example.com/index.html'))

With this patch, these methods can receive a URI-string.

Net::HTTP.get_response('http://www.example.com/index.html')

[k0kubun]

For consistency, supporting the same thing for Net::HTTP.post as well might be useful.

[kyanagi]

@k0kubun
Thank you for your suggestion.
I added the same support for Net::HTTP.post and Net::HTTP.post_form.