fix file.create: don't create an .empty folder on devices with new API support

feat docs: add Frequently Asked Questions section

README.md

@@ -9,11 +9,25 @@ Firefox OS 2.2 and up are supported. Sadly 2.0 and 1.3 miss a lot of ES6 functio
 
 ![Mobile Portrait Mockup](https://github.com/mdibaiee/Hawk/raw/master/Mobile%20Portrait.png)
 
-#Thanks to
+# Thanks to
 
 Sergio Muriel [@tfeserver](https://twitter.com/tfeserver) for testing application
 Mohammad Jahani [@mamal72](https://twitter.com/mamal72) for ideas, and helping in designing the [webpage](http://dibaiee.ir/Hawk)
 
+# Frequently Asked Questions
+
+**Q: Why does Hawk create an `.empty` file inside new folders I create?**
+
+This happens on Firefox OS devices below version 3, and that's because the API doesn't allow
+listing empty folders, in order to show you the folder, Hawk has to fake the folder to have a child.
+
+
+**Q: Why is Hawk slow?**
+
+Hawk is much faster on Firefox OS 3.0 and up, and that's because the way old Device Storage API works,
+it's slow by nature. Nothing we can do about it, sadly.
+
+
 # Features
 
 Version 1.0

build/main.js

@@ -30057,7 +30057,9 @@ var createDirectory = _asyncToGenerator(function* () {
   var parent = yield root();
 
   return parent.createDirectory.apply(parent, args).then(function () {
+    if (window.needsShim) {
       return createFile(args[0] + '/.empty');
+    }
   });
 });
 

build/polyfill.js

@@ -21,8 +21,11 @@ function Generator(){}function GeneratorFunction(){}function GeneratorFunctionPr
 	};
 }(Element.prototype));
 
+window.needsShim = false;
+
 function shimDirectory(directory) {
   if (!directory.getFilesAndDirectories) {
+		window.needsShim = true;
     directory.toString = function() { return '[object Directory]' };
     directory.getFilesAndDirectories = function getFilesAndDirectories() {
       var current = (this.path || '') + this.name;

src/js/api/files.js

@@ -84,7 +84,9 @@ export async function createDirectory(...args) {
   let parent = await root();
 
   return parent.createDirectory(...args).then(() => {
+    if (window.needsShim) {
       return createFile(args[0] + '/.empty');
+    }
   });
 }
 

src/polyfill.js

@@ -21,8 +21,11 @@ function Generator(){}function GeneratorFunction(){}function GeneratorFunctionPr
 	};
 }(Element.prototype));
 
+window.needsShim = false;
+
 function shimDirectory(directory) {
   if (!directory.getFilesAndDirectories) {
+		window.needsShim = true;
     directory.toString = function() { return '[object Directory]' };
     directory.getFilesAndDirectories = function getFilesAndDirectories() {
       var current = (this.path || '') + this.name;