Update zh-TW translation

Update text of "unexpected_response_error".
Merge pull request #5306 from xavier114fch/zh-TW

Update zh-TW translation
Fix setPreferences regression from the e10s patch (PR 5115)
Add back pdfBugEnabled pref check in the |log| function in extensions/firefox/content/PdfStreamConverter.jsm
Update the license header in extensions/firefox/content/pdfjschildbootstrap.js; see https://bugzilla.mozilla.org/show_bug.cgi?id=942707#c99