Cucumber should only run tests tagged both @clean and (@firefox or @phantomjs)

Paired with: Kartik Mistry

Already tested on mwext-browsertests-UniversalLanguageSelector-phantomjs[0] job.

[1]
...
...bundle exec cucumber --color --tags @clean...
...
13 scenarios (6 undefined, 7 passed)
...



[2]
...bundle exec cucumber --color --tags @clean --tags @phantomjs...
...
13 scenarios (6 undefined, 7 passed)
...



0: https://integration.wikimedia.org/ci/job/mwext-browsertests-UniversalLanguageSelector-phantomjs/jobConfigHistory/showDiffFiles?timestamp1=2014-03-31_09-46-31&timestamp2=2014-04-11_10-06-20
1: https://integration.wikimedia.org/ci/job/mwext-browsertests-UniversalLanguageSelector-phantomjs/367/console
2: https://integration.wikimedia.org/ci/job/mwext-browsertests-UniversalLanguageSelector-phantomjs/368/consol

Updates jobs:

mwext-browsertests-CirrusSearch-phantomjs
mwext-browsertests-Flow-firefox
mwext-browsertests-Flow-phantomjs
mwext-browsertests-MobileFrontend-firefox
mwext-browsertests-MobileFrontend-phantomjs
mwext-browsertests-Translatewiki-firefox
mwext-browsertests-Translatewiki-phantomjs
mwext-browsertests-UniversalLanguageSelector-firefox
mwext-browsertests-UniversalLanguageSelector-phantomjs
mwext-browsertests-VisualEditor-firefox
mwext-browsertests-VisualEditor-phantomjs

Change-Id: I2ea6ba84f2f55d7cfd12bfc7b82cec1a740142c6