browser acceptance tests

Apropos of https://www.mediawiki.org/wiki/Wikimedia_Release_and_QA_Team/Quarterly_review,_April_2014#Action_items

Tests pass on a bare wiki install, beta enwiki, beta dewiki, beta hewiki

Bug: 66272

Ported create_account.feature and supporting files from /qa/browsertest without needing updates
Change-Id: I2b4bfa512a33ff31cc0369dfd9ec19cb875d5e36
Merge "browser acceptance tests"