Set default hgk path for hgk outside bin.

--- a/hgext/hgk.py
+++ b/hgext/hgk.py
@@ -307,7 +307,7 @@
     "start interactive history viewer"
     os.chdir(repo.root)
     optstr = ' '.join(['--%s %s' % (k, v) for k, v in opts.iteritems() if v])
-    cmd = ui.config("hgk", "path", "hgk") + " %s %s" % (optstr, " ".join(etc))
+    cmd = ui.config("hgk", "path", "/usr/share/mercurial/hgk") + " %s %s" % (optstr, " ".join(etc))
     ui.debug("running %s\n" % cmd)
     util.system(cmd)