Revert "Replace OrderedDict by simple dict"

This reverts commit f29dae997ac26e5fcbd2eb037ed42028e54f2a6d.

This is usefull to control the order of how lxc.conf will
be written (especially for lxc.network.* values)

slapos/container/config.py

 # -*- coding: utf-8 -*-
 
+import collections
 import StringIO
 
 class LXCConfig(object):
@@ -38,7 +39,7 @@ class LXCConfig(object):
             with open(filename, 'r') as lxcconf_file:
                 self._values = self._load(lxcconf_file.read())
         else:
-            self._values = dict()
+            self._values = collections.OrderedDict()
 
     def __getattr__(self, name):
         return self._get(name)
@@ -50,7 +51,7 @@ class LXCConfig(object):
             self._set(name, value)
 
     def _load(self, config_string):
-        result = dict()
+        result = collections.OrderedDict()
         for line in config_string.split('\n'):
             if not line.strip().startswith('#') and line.strip() != '':
                 if '=' not in line: