Fix inverted scale factor for px units

Author: eKoopmans

src/html2pdf.js

@@ -294,7 +294,7 @@ var html2pdf = (function(html2canvas, jsPDF) {
       case 'mm':  k = 72 / 25.4;  break;
       case 'cm':  k = 72 / 2.54;  break;
       case 'in':  k = 72;         break;
-      case 'px':  k = 96 / 72;    break;
+      case 'px':  k = 72 / 96;    break;
       case 'pc':  k = 12;         break;
       case 'em':  k = 12;         break;
       case 'ex':  k = 6;          break;