Stop logging tracebacks when we're about to reraise

At that point, it's up to the caller to decide whether a stack trace is
appropriate; if the caller decides the connection error is recoverable,
us logging a traceback will only confuse things.

Also, prevent a TypeError during log interpolation by actually using the
argument we were providing.

kmip/pie/client.py

@@ -131,7 +131,7 @@ class ProxyKmipClient(object):
                 self.proxy.open()
                 self._is_open = True
             except Exception as e:
-                self.logger.exception("could not open client connection", e)
+                self.logger.error("could not open client connection: %s", e)
                 raise
 
     def close(self):
@@ -148,7 +148,7 @@ class ProxyKmipClient(object):
                 self.proxy.close()
                 self._is_open = False
             except Exception as e:
-                self.logger.exception("could not close client connection", e)
+                self.logger.error("could not close client connection: %s", e)
                 raise
 
     @is_connected