[mod] simple theme: include fonts

"npm run webfont" to build the fonts directory.
It requires fontforge and ttfautohint distro packages.

partial revert of commit 7137d2893f

searx/static/themes/simple/package.json

@@ -24,6 +24,7 @@
     "all": "npm install && grunt",
     "build": "grunt",
     "watch": "grunt watch",
+    "webfont": "grunt webfont",
     "clean": "rm -Rf node_modules package-lock.json ion.less"
   }
 }