feat(Participant): reuse avatar URL generation logic

It was moved to js-utils, so make use of it.

package.json

     "jquery-contextmenu": "2.4.5",
     "jquery-i18next": "1.2.0",
     "js-md5": "0.6.1",
+    "js-utils": "github:jitsi/js-utils#446497893023aa8dec403e0e4e35a22cae6bc87d",
     "jsc-android": "224109.1.0",
     "jsrsasign": "8.0.12",
     "jwt-decode": "2.2.0",

react/features/base/participants/functions.js

 // @flow
-import md5 from 'js-md5';
+import { getAvatarURL as _getAvatarURL } from 'js-utils/avatar';
 
 import { toState } from '../redux';
 
         return avatarURL;
     }
 
-    let key = email || avatarID;
-    let urlPrefix;
-    let urlSuffix;
-
-    // If the ID looks like an e-mail address, we'll use Gravatar because it
-    // supports e-mail addresses.
-    if (key && key.indexOf('@') > 0) {
-        urlPrefix = 'https://www.gravatar.com/avatar/';
-        urlSuffix = '?d=wavatar&size=200';
-    } else {
-        // Otherwise, we do not have much a choice but a random avatar (fetched
-        // from a configured avatar service).
-        if (!key) {
-            key = id;
-            if (!key) {
-                return undefined;
-            }
-        }
-
-        // The deployment is allowed to choose the avatar service which is to
-        // generate the random avatars.
-        urlPrefix
-            = typeof interfaceConfig === 'object'
-                && interfaceConfig.RANDOM_AVATAR_URL_PREFIX;
-        if (urlPrefix) {
-            urlSuffix = interfaceConfig.RANDOM_AVATAR_URL_SUFFIX;
-        } else {
-            // Otherwise, use a default (meeples, of course).
-            urlPrefix = 'https://abotars.jitsi.net/meeple/';
-            urlSuffix = '';
-        }
-    }
-
-    return urlPrefix + md5.hex(key.trim().toLowerCase()) + urlSuffix;
+    // The deployment is allowed to choose the avatar service which is to
+    // generate the random avatars.
+    const avatarService
+        = typeof interfaceConfig === 'object'
+                && interfaceConfig.RANDOM_AVATAR_URL_PREFIX
+            ? {
+                urlPrefix: interfaceConfig.RANDOM_AVATAR_URL_PREFIX,
+                urlSuffix: interfaceConfig.RANDOM_AVATAR_URL_SUFFIX }
+            : undefined;
+
+    // eslint-disable-next-line object-property-newline
+    return _getAvatarURL({ avatarID, email, id }, avatarService);
 }
 
 /**

webpack.config.js

     = process.argv.indexOf('-p') !== -1
         || process.argv.indexOf('--optimize-minimize') !== -1;
 
-// eslint-disable-next-line camelcase
-const node_modules = `${__dirname}/node_modules/`;
 const plugins = [
     new webpack.LoaderOptionsPlugin({
         debug: !minimize,
             // Transpile ES2015 (aka ES6) to ES5. Accept the JSX syntax by React
             // as well.
 
-            exclude: node_modules, // eslint-disable-line camelcase
+            exclude: [
+                new RegExp(`${__dirname}/node_modules/(?!js-utils)`)
+            ],
             loader: 'babel-loader',
             options: {
                 // XXX The require.resolve bellow solves failures to locate the