Fixes some client.py exceptions for Python 3.

This fixes two problems:

1) The exception syntax rework incorrectly updated two except clauses
to use the new *raise* syntax rather than the new *except* syntax.

2) In Python 3, exception objects are local to the try/except block,
making them inaccessible outside that block.  It was probably actually
an error to set the "message" to be the exception object rather than
its string representation, anyway.

TESTED:
Ran xgps without gpsd running, and verified that the proper error box
is displayed, in both Python 2 and Python 3 (with appropriate builds
of the extensions).  Didn't test the gpsjson.unpack ValueError case,
but the syntax is the same.

gps/client.py

@@ -67,7 +67,8 @@ def connect(self, host, port):
                 self.sock = socket.socket(af, socktype, proto)
                 # if self.debuglevel > 0: print 'connect:', (host, port)
                 self.sock.connect(sa)
-            except socket.error(msg):
+            except socket.error as e:
+                msg = str(e)
                 # if self.debuglevel > 0: print 'connect fail:', (host, port)
                 self.close()
                 continue
@@ -161,7 +162,7 @@ def __iter__(self):
     def unpack(self, buf):
         try:
             self.data = dictwrapper(json.loads(buf.strip(), encoding="ascii"))
-        except ValueError(e):
+        except ValueError as e:
             raise json_error(buf, e.args[0])
         # Should be done for any other array-valued subobjects, too.
         # This particular logic can fire on SKY or RTCM2 objects.