Remove unused method 'from_response'

'openstackclient.common.exceptions.from_response' method is never called
in openstackclient code base, so we should remove it.

Change-Id: I04254a4e66863942e6c273d77bbd66ce2ce7804c
Related-Bug: #1559072

openstackclient/common/exceptions.py

@@ -108,28 +108,3 @@ _code_map = dict((c.http_status, c) for c in [
     OverLimit,
     HTTPNotImplemented
 ])
-
-
-def from_response(response, body):
-    """Return an instance of a ClientException based on an httplib2 response.
-
-    Usage::
-
-        resp, body = http.request(...)
-        if resp.status != 200:
-            raise exception_from_response(resp, body)
-    """
-    cls = _code_map.get(response.status, ClientException)
-    if body:
-        if hasattr(body, 'keys'):
-            error = body[list(body.keys())[0]]
-            message = error.get('message')
-            details = error.get('details')
-        else:
-            # If we didn't get back a properly formed error message we
-            # probably couldn't communicate with Keystone at all.
-            message = "Unable to communicate with image service: %s." % body
-            details = None
-        return cls(code=response.status, message=message, details=details)
-    else:
-        return cls(code=response.status)