geckodriver: changes: update

Source-Repo: https://github.com/mozilla/geckodriver
Source-Revision: 8077ee81cec9b39e2e6a47eaee2f82f6e0991ad7

--HG--
extra : rebase_source : 8e94198a707b08af624ceb0355c441738fbdcd4a

testing/geckodriver/CHANGES.md

@@ -2,6 +2,16 @@
 
 All notable changes to this program is documented in this file.
 
+## 0.14.0 (2017-01-31)
+
+### Changed
+- Firefox process is now terminated and session ended when the last window is closed
+- WebDriver library updated to version 0.20.0
+
+### Fixed
+- Stacktraces are now included when the error originates from within the Rust stack
+- HTTPD now returns correct response headers for `Content-Type` and `Cache-Control` thanks to @jugglinmike
+
 ## 0.13.0 (2017-01-06)
 
 ### Changed