Set /app PHP code to PSR-2 standard

Also adde draw.io to attribution list.

Closes #649

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "7d60f09393b99551e9ffdb6622ed7ade",
+    "content-hash": "8ad5cb7acc1115a77404d1be899984ac",
     "packages": [
         {
             "name": "aws/aws-sdk-php",
@@ -5027,6 +5027,57 @@
             "homepage": "https://github.com/sebastianbergmann/version",
             "time": "2016-10-03T07:35:21+00:00"
         },
+        {
+            "name": "squizlabs/php_codesniffer",
+            "version": "3.2.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/squizlabs/PHP_CodeSniffer.git",
+                "reference": "d7c00c3000ac0ce79c96fcbfef86b49a71158cd1"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/squizlabs/PHP_CodeSniffer/zipball/d7c00c3000ac0ce79c96fcbfef86b49a71158cd1",
+                "reference": "d7c00c3000ac0ce79c96fcbfef86b49a71158cd1",
+                "shasum": ""
+            },
+            "require": {
+                "ext-simplexml": "*",
+                "ext-tokenizer": "*",
+                "ext-xmlwriter": "*",
+                "php": ">=5.4.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.0 || ^5.0 || ^6.0"
+            },
+            "bin": [
+                "bin/phpcs",
+                "bin/phpcbf"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.x-dev"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Greg Sherwood",
+                    "role": "lead"
+                }
+            ],
+            "description": "PHP_CodeSniffer tokenizes PHP, JavaScript and CSS files and detects violations of a defined set of coding standards.",
+            "homepage": "http://www.squizlabs.com/php-codesniffer",
+            "keywords": [
+                "phpcs",
+                "standards"
+            ],
+            "time": "2017-12-19T21:44:46+00:00"
+        },
         {
             "name": "symfony/class-loader",
             "version": "v3.3.6",