Migrate to json based i18n files

Used I4b8f1d9 for the conversion, so the shim was added automatically. The
script was run on Windows 7 with PHP 5.3.6.

php \branches\mediawiki\core\maintenance\generateJsonI18n.php FirstSteps.i18n.php i18n\firststeps
php \branches\mediawiki\core\maintenance\generateJsonI18n.php PageTranslation.i18n.php i18n\pagetranslation
php \branches\mediawiki\core\maintenance\generateJsonI18n.php Translate.i18n.php i18n\core
php \branches\mediawiki\core\maintenance\generateJsonI18n.php TranslateGroupDescriptions.i18n.php i18n\groupdescriptions
php \branches\mediawiki\core\maintenance\generateJsonI18n.php TranslateSandbox.i18n.php i18n\sandbox
php \branches\mediawiki\core\maintenance\generateJsonI18n.php TranslateSearch.i18n.php i18n\search

Change-Id: Iac22f6fddbe0b5e26777dc13f2f375de74c51bdd