Ability to set request timeout, made opts parameters optional

[DaWe35]

This PR includes two backward-compatible updates.

• Ability to set the request timeout
• The ability to NOT to set all opts parameters. Previously if you wanted to pass the opts parameter, it was mandatory to declare all variables in the opts object. Now you can declare the variables that are important for you, and leave the rest default. Example:

  opts = type('obj', (object,), {
  'portal_url': portal,
  'timeout': 20
  })
  skylink = Skynet.upload_file('2MBfile.txt', opts)

Complete example for upload (source):

opts = type('obj', (object,), {
    'portal_url': portal,
    'timeout': 20
})
try:
    try:
        skylink = Skynet.upload_file('file.txt', opts)
        print(skylink)
    except TimeoutError as e:
        # timed out

except Exception as e:
    # other error

[marcinja]

Looks good to me. Just needs the changes m-cat already mentioned.

[DaWe35]

@m-cat 1. What about making default_upload_options and default_download_options able to handle deficient opts? I mean do we really need the fill_with... functions?

2. agree

[mrcnski]

@m-cat 1. What about making default_upload_options and default_download_options able to handle deficient opts? I mean do we really need the fill_with... functions?

Interesting idea. In my opinion the default_ functions should just return the default opts as before. I don't see the reason for a user to pass in a deficient opts, the upload and download methods will just fill in the missing opts anyway. I would keep the default_ functions simple, behaving the same way as in the other SDKs, while we make the fill_with functions private. This way we don't complicate the API at all and still have elegant option-filling internally.

[mrcnski]

@DaWe35 Since these are static methods there is no class instance, you need to do Skynet.fill_with_default_upload_options()

[mrcnski]

Okay, I've seen you've done that. Looks great to me! Will give it one more look-through.