tuna config: Fix pygtk import

We should 'import gtk', not 'import pygtk', fixes bugs when the error
paths try to use gtk.messageDialog():

[root@ssdandy tuna]# tuna
Traceback (most recent call last):
  File "/home/acme/git/tuna/tuna-cmd.py", line 654, in <module>
  File "/home/acme/git/tuna/tuna-cmd.py", line 648, in main
    app = tuna_gui.main_gui(kthreads, uthreads, cpus_filtered)
  File "/home/acme/git/tuna/tuna/tuna_gui.py", line 64, in __init__
  File "/home/acme/git/tuna/tuna/gui/profileview.py", line 141, in
    not self.config.load(self.config.config['lastfile']):
  File "/home/acme/git/tuna/tuna/config.py", line 48, in load
    if(self.tuned2Tuna(profileName) < 0):
  File "/home/acme/git/tuna/tuna/config.py", line 66, in tuned2Tuna
    dialog = gtk.MessageDialog(None, 0, gtk.MESSAGE_ERROR,\
NameError: global name 'gtk' is not defined
[root@ssdandy tuna]#

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tuna/config.py b/tuna/config.py
index 77cc4d8..7e19a28 100644
--- a/tuna/config.py
+++ b/tuna/config.py
@@ -1,5 +1,5 @@
 import io, os, re, fnmatch
-import sys, pygtk
+import sys, gtk
 import codecs, ConfigParser
 from time import localtime, strftime
 from subprocess import Popen, PIPE, STDOUT, call