Set default hgk path for hgk outside bin.

--- mercurial.orig/hgext/hgk.py
+++ mercurial/hgext/hgk.py
@@ -65,7 +65,7 @@ configtable = {}
 configitem = registrar.configitem(configtable)
 
 configitem('hgk', 'path',
-    default='hgk',
+    default='/usr/share/mercurial/hgk',
 )
 
 @command('debug-diff-tree',