Drop messy py26 support in favour of 100% coverage

.travis.yml

@@ -1,13 +1,11 @@
 language: python
 env: # These should match the tox env list
-    - TOXENV=py26
     - TOXENV=py27
     - TOXENV=py33
     - TOXENV=py34
     - TOXENV=pypy
     - TOXENV=pypy3
 install:
-    - if [[ $TOXENV == py26 ]]; then pip install ordereddict; fi
     - pip install coveralls tox
 script: tox
 # Special snowflake.  Our tests depend on making real commits.

pre_commit_hooks/pretty_format_json.py

@@ -2,13 +2,7 @@ from __future__ import print_function
 
 import argparse
 import sys
-
-# Versions older than Python 2.6 will need to install ordereddict,
-# but newer versions will import from the built-in collections module.
-try:
-    from collections import OrderedDict
-except ImportError:
-    from ordereddict import OrderedDict
+from collections import OrderedDict
 
 import simplejson