chore: get rid of gulp (#593)

The only thing we were still using gulp for was compiling SCSS.

Signed-off-by: Juan Cruz Viotti <jviottidc@gmail.com>

build/css/main.css

@@ -6676,3 +6676,4 @@ body {
   .section-header > .btn, .section-header > .progress-button {
     padding-left: 3px;
     padding-right: 3px; }
+

docs/CONTRIBUTING.md

@@ -15,7 +15,6 @@ Prerequisites
 
 - [NodeJS](https://nodejs.org).
 - [Bower](http://bower.io).
-- [Gulp](http://gulpjs.com).
 - [UPX](http://upx.sourceforge.net).
 - [Python](https://www.python.org).
 
@@ -77,24 +76,10 @@ node bin/etcher
 Developing
 ----------
 
-We rely on [gulp] to provide an automated developing workflow in which your
-changes will automatically be detected and the necessary resources will be
-rebuilt for you.
+We rely on various `npm` scripts to perform some common tasks:
 
-First make sure you have [gulp] installed as a global dependency:
-
-```sh
-$ npm install -g gulp
-```
-
-Run the `watch` task to initialise the build system. We encourage to have this
-command running in the background all the time as you develop, and check the
-output from time to time, since it'll let you know of any issues and/or
-warnings in your changes:
-
-```js
-$ gulp watch
-```
+- `npm run lint`: Run the linter.
+- `npm run sass`: Compile SCSS files.
 
 We make use of [EditorConfig] to communicate indentation, line endings and
 other text editing default. We encourage you to install the relevant plugin in
@@ -126,11 +111,6 @@ Use the following steps to ensure everything goes flawlessly:
 Testing
 -------
 
-In order to avoid inaccurate results, the test suites run in a real Electron
-instance each in the respective process. This means that running the test suite
-is not a cheap operation and therefore we decided to not run it by default in
-the `watch` gulp task to not disrupt the user development workflow.
-
 To run the test suite, run the following command:
 
 ```sh
@@ -194,7 +174,6 @@ systems we support.
 Don't hesitate to get in touch if you have any questions or need any help!
 
 [ARCHITECTURE]: https://github.com/resin-io/etcher/blob/master/docs/ARCHITECTURE.md
-[gulp]: http://gulpjs.com
 [EditorConfig]: http://editorconfig.org
 [commitizen]: https://commitizen.github.io/cz-cli/#making-your-repo-commitizen-friendly
 [shrinkwrap]: https://docs.npmjs.com/cli/shrinkwrap

gulpfile.js

@@ -1,42 +0,0 @@
-/*
- * Copyright 2016 Resin.io
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-'use strict';
-
-const gulp = require('gulp');
-const sass = require('gulp-sass');
-
-const paths = {
-  scripts: [
-    './tests/**/*.spec.js',
-    './lib/**/*.js',
-    'gulpfile.js'
-  ],
-  sass: [
-    './lib/gui/**/*.scss'
-  ],
-  sassMain: './lib/gui/scss/main.scss'
-};
-
-gulp.task('sass', function() {
-  return gulp.src(paths.sassMain)
-    .pipe(sass().on('error', sass.logError))
-    .pipe(gulp.dest('./build/css'));
-});
-
-gulp.task('watch', [ 'sass' ], function() {
-  gulp.watch(paths.sass, [ 'sass' ]);
-});

package.json

@@ -11,7 +11,8 @@
   },
   "scripts": {
     "test": "npm run lint && electron-mocha --recursive --renderer tests/gui -R min",
-    "lint": "eslint gulpfile.js lib tests scripts bin",
+    "sass": "node-sass ./lib/gui/scss/main.scss > build/css/main.css",
+    "lint": "eslint lib tests scripts bin",
     "start": "electron lib/start.js",
     "shrinkwrap": "node ./scripts/shrinkwrap.js"
   },
@@ -27,7 +28,6 @@
     "assets/osx",
     "appveyor.yml",
     "bower.json",
-    "gulpfile.js",
     "screenshot.png",
     "tests",
     "etcher-release",
@@ -97,10 +97,9 @@
     "electron-packager": "^7.0.1",
     "electron-prebuilt": "1.2.6",
     "eslint": "^2.13.1",
-    "gulp": "^3.9.0",
-    "gulp-sass": "^2.0.4",
     "jsonfile": "^2.3.1",
-    "mochainon": "^1.0.0"
+    "mochainon": "^1.0.0",
+    "node-sass": "^3.8.0"
   },
   "config": {
     "commitizen": {