[CRX] Stop intercepting ftp in Chrome 59+
[CRX] Stop intercepting ftp in Chrome 59+

The extension cannot easily fetch data from ftp:-resources any more
in Chrome 59+. So don't intercept such URLs.

mukulmishra18/pdf.js,showpad/mozilla-pdf.js,Snuffleupagus/pdf.js,Shoobx/pdf.js,mozilla/pdf.js,timvandermeij/pdf.js,caremerge/pdf.js,Shoobx/pdf.js,Snuffleupagus/pdf.js,mainegreen/pdf.js,mozilla/pdf.js,mozilla/pdf.js,showpad/mozilla-pdf.js,timvandermeij/pdf.js,xavier114fch/pdf.js,Snuffleupagus/pdf.js,mainegreen/pdf.js,nawawi/pdf.js,macroplant/pdf.js,showpad/mozilla-pdf.js,nawawi/pdf.js,macroplant/pdf.js,Shoobx/pdf.js,timvandermeij/pdf.js,macroplant/pdf.js,caremerge/pdf.js,xavier114fch/pdf.js,mukulmishra18/pdf.js,nawawi/pdf.js