Version bump; add changelog

.version

@@ -1 +1 @@
-0.5.2
+0.5.3

doc/CHANGELOG.md

@@ -0,0 +1,7 @@
+# octocatalog-diff change log
+
+| Version | Date | Description / Changes |
+| ------- | ---- | ----------- |
+| 0.5.3   | 2016-10-31 | https://github.com/github/octocatalog-diff/pull/10: facts terminus optimization |
+| 0.5.2   | - | Unreleased internal version |
+| 0.5.1   | 2016-10-20 | Initial release |