merging PR Chaosthebot#433: Add ESLint to lint JS files

Chaosthebot#433: Add ESLint to lint JS files

Description:
Currently uses `eslint-config-airbnb` with indents of 4 and double quotes.

:ok_woman: PR passed with a vote of 13 for and 1 against, a weighted total of 11.5 and a threshold of 6.6, and a current meritocracy review.

Vote record:
@Leigende: 1
@MUCHZER: 1
@Moussto: 1
@PlasmaPower: 1
@RyanZim: 1
@Smittyvb: 1
@andrewda: 1
@dcstone09: 1
@eukaryote31: 1
@hongaar: 1
@md678685: 1
@qgustavor: -1
@rhengles: 1
@viktorsec: 1

.eslintrc

@@ -0,0 +1,16 @@
+{
+    "extends": "airbnb",
+    "env": {
+        "browser": true,
+        "jquery": true
+    },
+    "plugins": [
+        "jquery"
+    ],
+    "rules": {
+        "quotes": ["error", "double", {"allowTemplateLiterals": true}],
+        "indent": ["error", 4],
+        "no-console": "off",
+        "no-mixed-operators": "off"
+    }
+}

.travis.yml

@@ -2,9 +2,13 @@ language: python
 python:
   - "3.6"
 install:
+  - "nvm install node"
+  - "nvm use node"
+  - "npm install -g eslint@^3.19.0 eslint-plugin-jquery@latest eslint-plugin-jsx-a11y@^5.0.1 eslint-plugin-import@^2.2.0 eslint-plugin-react@^7.0.1 eslint-config-airbnb"
   - "pip install -r requirements.txt"
   - "pip install flake8"
 cache: pip
 script:
   - flake8
   - python -m unittest discover -p "*_test.py"
+  - "eslint ./server/static/js/"