Add open coded OpenStruct

Author: Werkov

git_explode/exploder.py

@@ -3,7 +3,6 @@
 
 import copy
 import six
-from ostruct import OpenStruct
 
 from git_deps.detector import DependencyDetector
 from git_deps.gitutils import GitUtils
@@ -12,6 +11,11 @@
 from git_explode.listener import ExplodeDependencyListener
 from git_explode.topics import TopicManager
 
+class OpenStruct:
+    def __init__(self, data):
+        self.__dict__.update(data)
+    def __getattr__(self, key):
+        return self.__dict__[key] if key in self.__dict__ else None
 
 class GitExploder(object):
     """Explode a linear sequence of git commits into multiple independent