(testing) added Selenium tests for setDescription special page

- extended and refactored setLabel test to be able to test
setDescription and others too

Change-Id: Ie4f7067b2e3c9f743fe7e312e9712261ead9d8fb
(testing) added selenium test for setAliases special page

Change-Id: I58c06d0f6f34999229faa57445050048ebbb93fd
Merge "(testing) added Selenium tests for setDescription special page"
Merge "(testing) added selenium test for setAliases special page"