Update obsolete link for mobile json wire protocol spec. (#257)

Author: andreip

README.md

@@ -3,7 +3,7 @@ Appium Python Client
 
 [![PyPI version](https://badge.fury.io/py/Appium-Python-Client.svg)](https://badge.fury.io/py/Appium-Python-Client)
 
-An extension library for adding [Selenium 3.0 draft](https://dvcs.w3.org/hg/webdriver/raw-file/tip/webdriver-spec.html) and [Mobile JSON Wire Protocol Specification draft](https://code.google.com/p/selenium/source/browse/spec-draft.md?repo=mobile)
+An extension library for adding [Selenium 3.0 draft](https://dvcs.w3.org/hg/webdriver/raw-file/tip/webdriver-spec.html) and [Mobile JSON Wire Protocol Specification draft](https://github.com/SeleniumHQ/mobile-spec/blob/master/spec-draft.md)
 functionality to the Python language bindings, for use with the mobile testing
 framework [Appium](https://appium.io).