helper.js and fs-extra fixes

[Problem] helper.js name could be misleading. getTemplateContent
function in library.js works more predictable with sync version of
writeFile
[Solution] I've changed helper.js name to more descriptive. Also I've
change writeFile to writeFileSync in getTemplateContent.

Signed-off-by: Hubert Siwkin <h.siwkin@samsung.com>

design-editor/src/pane/design-editor.js

@@ -943,7 +943,7 @@ class Model {
         // }
 
 		this._DOM.body.appendChild(scriptRunner);
-		this.addLibrary('helper.js');
+		this.addLibrary('back-button-support.js');
 		if (screen.shape == 'circle') {
 			this.addLibrary('tau.circle.css');
 			this.addLibrary('circle-helper.js');

design-editor/src/system/libraries/library.js

@@ -84,7 +84,7 @@ class Library {
 			if (!exists) {
 				this.getTemplateContent()
 					.then((text) => {
-						return writeFile(this.getAbsolutePath(), text);
+						return fs.writeFileSync(this.getAbsolutePath(), text);
 					})
 					.then(callback)
 					.catch(err => {throw err;});

vsc-extension/design-editor/libs/fs-extra.js

@@ -85,9 +85,11 @@ function makeDir(path, callback) {
  * Writes data to file specified via name argument.
  * Triggers callback afterwards.
  *
- * @param {String} path path starting from the project root
+ * @param {String} path Path starting from the project root
  * @param {Object} data
- * @param {Function} callback
+ * @param {Function} callback Callback function triggered after
+ * the writing to file is done
+ * @param {Object} [additionalOptions]
  */
 function writeFile(path, data, callback, additionalOptions = {}) {
 	const options = {
@@ -102,6 +104,21 @@ function writeFile(path, data, callback, additionalOptions = {}) {
 	__fetchHelper(fileEndpoint, options, 'text', callback);
 }
 
+/**
+ * Synchronous version of writeFile
+ *
+ * @todo implement synchronous version of writeFile
+ * (for now it's here just for WATT compability pourposes)
+ * @param {String} path Path starting from the project root
+ * @param {Object} data
+ * @param {Function} callback Callback function triggered after
+ * the writing to file is done
+ * @param {Object} [additionalOptions]
+ */
+function writeFileSync(path, data, callback, additionalOptions = {}) {
+	writeFile(path, data, callback, additionalOptions);
+}
+
 /**
  * Checks if file specified in name exists,
  * triggers callback afterwards.
@@ -143,6 +160,7 @@ function readDir(URL, callback) {
 module.exports = {
 	readFile,
 	writeFile,
+	writeFileSync,
 	makeDir,
 	existsDir,
 	exists,