Don't specify Host header explicitly (#673)

Just let the http lib handle that for us, we shouldn't be doing
that here at all.

Currently we are not handling punycode (if used) and ports, this
way we don't have to care about this and just let the lib do the best
thing.

Author: mateusz834

splunklib/binding.py

@@ -1559,7 +1559,6 @@ def request(url, message, **kwargs):
         body = message.get("body", "")
         head = {
             "Content-Length": str(len(body)),
-            "Host": host,
             "User-Agent": "splunk-sdk-python/%s" % __version__,
             "Accept": "*/*",
             "Connection": "Close",