Merge pull request #272 from d11wtq/bugfix/race_condition

Update dockerpty to fix discovered race condition.

requirements.txt

@@ -3,4 +3,4 @@ PyYAML==3.10
 requests==2.2.1
 texttable==0.8.1
 websocket-client==0.11.0
-dockerpty==0.0.8
+dockerpty==0.1.0