Improve ESLint rules

bigbluebutton-html5/.eslintignore

 tests/*
+Gruntfile.js

bigbluebutton-html5/.eslintrc.js

@@ -5,9 +5,18 @@ module.exports = {
         "jsx-a11y",
         "import",
     ],
+    "env": {
+      "es6": true,
+      "node": true,
+      "browser": true,
+      "meteor": true,
+    },
     "rules": {
+      "no-underscore-dangle": 0,
       "import/extensions":  [2, "never"],
       "import/no-absolute-path": 0,
       "import/no-unresolved": 0,
+      "import/no-extraneous-dependencies": 1,
+      "react/prop-types": 1,
     },
 };