pythong needs files listed in the manifest too :(

Author: lukeis

MANIFEST.in

@@ -6,7 +6,7 @@ recursive-include py/selenium/common *.py
 recursive-include py/selenium/webdriver/chrome *.py
 recursive-include py/selenium/webdriver/opera *.py
 recursive-include py/selenium/webdriver/phantomjs *.py
-recursive-include py/selenium/webdriver/firefox *.py *.xpi
+recursive-include py/selenium/webdriver/firefox *.py *.xpi *.json
 recursive-include py/selenium/webdriver/firefox/x86 *.so
 recursive-include py/selenium/webdriver/firefox/amd64 *.so
 recursive-include py/selenium/webdriver/ie *.py