Issue #2871003 by jungle, lluisandreu: Adopt composer-merge-plugin to make...

Issue #2871003 by jungle, lluisandreu: Adopt composer-merge-plugin to make managing the enyo/dropzone library easier

.editorconfig

+# @see http://editorconfig.org/
+
+[composer.libraries.json]
+indent_size = 4
+indent_style = space

README.md

-## About DropzoneJS
+# About DropzoneJS
 
 This is the Drupal integration for [DropzoneJS](http://www.dropzonejs.com/).
 
-###How to install:
+### How to install
+
+#### The non-composer way
+
 1. Download this module
 2. [Download DropzoneJS](https://github.com/enyo/dropzone) and place it in the
    libraries folder
@@ -12,25 +15,68 @@ This is the Drupal integration for [DropzoneJS](http://www.dropzonejs.com/).
 
 You will now have a dropzonejs element at your disposal.
 
-###Future plans:
+#### The composer way 1
+
+Run `composer require wikimedia/composer-merge-plugin`
+
+Update the root `composer.json` file. For example:
+
+```
+    "extra": {
+        "merge-plugin": {
+            "include": [
+                "web/modules/contrib/dropzonejs/composer.libraries.json"
+            ]
+        }
+    }
+```
+
+Run `composer require drupal/dropzonejs enyo/dropzone`, the DropzoneJS library will be
+installed to the `libraries` folder automatically.
+
+#### The composer way 2
+
+Copy the following into the root `composer.json` file's `repository` key
+
+```
+    "repositories": [
+        {
+            "type": "package",
+            "package": {
+                "name": "enyo/dropzone",
+                "version": "5.7.1",
+                "type": "drupal-library",
+                "dist": {
+                    "url": "https://github.com/enyo/dropzone/archive/v5.7.1.zip",
+                    "type": "zip"
+                }
+            }
+        }
+    ]
+```
+
+Run `composer require drupal/dropzonejs enyo/dropzone`, the DropzoneJS library
+will be installed to the `libraries` folder automatically as well.
+
+### Future plans:
 - A dropzonejs field widget.
 - Handling already uploaded files.
 - Handling other types of upload validations (min/max resolution, min size,...)
 - Removing files that were removed by the user on first upload from temp storage.
 
-###Project page:
+### Project page:
 [drupal.org project page](https://www.drupal.org/project/dropzonejs)
 
-###Maintainers:
+### Maintainers:
 + Janez Urevc (@slashrsm) drupal.org/u/slashrsm
 + John McCormick (@neardark) drupal.org/u/neardark
 + Primoz Hmeljak (@primsi) drupal.org/u/Primsi
 + Qiangjun Ran (@jungle) drupal.org/u/jungle
 
-###Get in touch:
+### Get in touch:
  - http://groups.drupal.org/media
  - **#media**: http://drupal.slack.com
 
-###Thanks:
+### Thanks:
  The development of this module is sponsored by [Examiner.com](http://www.examiner.com)
  Thanks also to [NYC CAMP](http://nyccamp.org/) that hosted media sprints.

composer.libraries.json

+{
+    "repositories": {
+        "enyo/dropzone": {
+            "type": "package",
+            "package": {
+                "name": "enyo/dropzone",
+                "version": "5.7.1",
+                "type": "drupal-library",
+                "dist": {
+                    "url": "https://github.com/enyo/dropzone/archive/v5.7.1.zip",
+                    "type": "zip"
+                }
+            }
+        }
+    },
+    "require": {
+        "enyo/dropzone": "5.7.1"
+    }
+}