fix wrong Row number in DiscoveryDialog.py that caused following traceback:

Traceback (most recent call last):
File "/home/beremiz/beremiz/ProjectController.py", line 1536, in _Connect
dialog = DiscoveryDialog(self.AppFrame)
File "/home/beremiz/beremiz/dialogs/DiscoveryDialog.py", line 124, in __init__
self._init_ctrls(parent)
File "/home/beremiz/beremiz/dialogs/DiscoveryDialog.py", line 121, in _init_ctrls
self._init_sizers()
File "/home/beremiz/beremiz/dialogs/DiscoveryDialog.py", line 73, in _init_sizers
self._init_coll_ButtonGridSizer_Growables(self.ButtonGridSizer)
File "/home/beremiz/beremiz/dialogs/DiscoveryDialog.py", line 64, in _init_coll_ButtonGridSizer_Growables
parent.AddGrowableRow(1)
File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk2/wx/_core.py", line 15343, in AddGrowableRow
return _core_.FlexGridSizer_AddGrowableRow(*args, **kwargs)
PyAssertionError: C++ assertion "!m_rows || idx < (size_t)m_rows" failed at ../src/common/sizer.cpp(1967) in AddGrowableRow(): invalid row index

--- a/dialogs/DiscoveryDialog.py	Thu Apr 21 17:44:17 2016 +0300
+++ b/dialogs/DiscoveryDialog.py	Thu Apr 21 17:47:35 2016 +0300
@@ -61,7 +61,7 @@
     def _init_coll_ButtonGridSizer_Growables(self, parent):
         parent.AddGrowableCol(0)
         parent.AddGrowableCol(1)
-        parent.AddGrowableRow(1)
+        parent.AddGrowableRow(0)
     
     def _init_sizers(self):
         self.MainSizer = wx.FlexGridSizer(cols=1, hgap=0, rows=3, vgap=10)