chore(jshint): remove JSHint

.jshintignore

-# The following do not need to be checked because they do not represent JS
-# source code.
-doc/
-node_modules/
-lib-jitsi-meet.js
-lib-jitsi-meet.js.map
-lib-jitsi-meet.min.js
-
-# The following are checked by ESLint and take advantage of advanced language
-# features such as Facebook Flow which are not supported by JSHint.
-flow-typed/

.jshintrc

-{
-    "browser": true, // Web Browser (window, document, etc)
-    "esversion": 6,
-    "expr": true, // true: Tolerate `ExpressionStatement` as Programs
-    "jasmine": true,
-    "latedef": false, //This option prohibits the use of a variable before it was defined
-    "laxbreak": true, //Ignore line breaks around "=", "==", "&&", etc.
-    "loopfunc": true, // true: Tolerate functions being defined in loops
-    "node": true // Node.js
-}

modules/xmpp/RtxModifier.spec.js

 /* eslint-disable max-len*/
 /* eslint-disable no-invalid-this */
-/* jshint maxlen:false*/
 import RtxModifier from './RtxModifier.js';
 import * as SampleSdpStrings from './SampleSdpStrings.js';
 import * as transform from 'sdp-transform';

modules/xmpp/SampleSdpStrings.js

 /* eslint-disable max-len*/
-/* jshint maxlen:false*/
 import * as transform from 'sdp-transform';
 
 // A generic sdp session block

package.json

     "eslint-plugin-import": "2.3.0",
     "flow-bin": "0.38.0",
     "jasmine-core": "2.5.2",
-    "jshint": "2.9.4",
     "karma": "0.13.22",
     "karma-chrome-launcher": "0.2.3",
     "karma-jasmine": "0.3.8",
     "webpack": "2.6.1"
   },
   "scripts": {
-    "lint": "jshint . && eslint . && flow",
+    "lint": "eslint . && flow",
     "postinstall": "webpack -p",
     "test": "karma start karma.conf.js",
     "validate": "npm ls"