Removed Python 2.6 support

* Travis CI doesn't support it anymore.
* It had EOL more than 4 years ago

httpie/utils.py

@@ -1,12 +1,9 @@
 from __future__ import division
 import json
-
-from httpie.compat import is_py26, OrderedDict
+from collections import OrderedDict
 
 
 def load_json_preserve_order(s):
-    if is_py26:
-        return json.loads(s)
     return json.loads(s, object_pairs_hook=OrderedDict)