Merge pull request #951 from docker/1.7.2-release

Prepare 1.7.2 release

docker/version.py

-version = "1.8.0-dev"
+version = "1.7.2"
 version_info = tuple([int(d) for d in version.split("-")[0].split(".")])

docs/change_log.md

 Change Log
 ==========
 
+1.7.2
+-----
+
+[List of PRs / issues for this release](https://github.com/docker/docker-py/issues?q=milestone%3A1.7.2+is%3Aclosed)
+
+### Bugfixes
+
+* Fixed a bug where TLS verification was improperly executed when providing
+  a custom CA certificate.
+
 1.7.1
 -----