Disable JavaScript for MSIE7 users, update tests accordingly

MSIE7 is outdated and unsupported (on Windows XP). It has several unpatched
security vulnerabilities. [1] Supporting its JavaScript engine requires
significant testing and development effort which is better spent
elsewhere.

This effectively demotes MSIE7 to "Grade C" status per the MediaWiki
browser compatibility standards. [2]

More detailed justification in [3].

[1] http://secunia.com/community/advisories/product/12366
[2] https://www.mediawiki.org/wiki/Compatibility#Grade_C
[3] https://lists.wikimedia.org/pipermail/wikitech-l/2014-August/077958.html

Change-Id: I2ce43dd94aba1aab947e51857d374fb9ed164228