AzureBlobFileSystem: remove socket_timeout

[dtrifiro]

socket_timeout option is not being used

closes #303

[TomAugspurger]

Thanks! Could you do this as a deprecation warning to avoid breaking code that was passing that?

Since we use None for the default, you'd need something like

# top-level
_socket_timeout_default = object()

def __init__(self, ... socket_timeout=_socket_timeout_default, ...):
    # in __init__
    if socket_timeout is not _socket_timeout_default:
        warnings.warn("message", FutureWarning)

[falkerson]

Hi folks, how to set timeout then? For example in #112 it isn't clear what was happening, it just was closed. What if process hang on waiting data or something? How we can force methods like read_block to raise some exception instead of wait indefinitely and waste resource?