Add code linting

This adds code linting using a .coafile which checks using the
ESLintBear, SpaceConsistencyBear, LineLengthBear and
InvalidLinkBear.

Closes #11

Author: andrewda

.coafile

@@ -0,0 +1,31 @@
+[all]
+files = *.js
+max_line_length = 80
+use_spaces = True
+eslint_config = .eslintrc
+
+[all.whitespace]
+bears = SpaceConsistencyBear
+default_actions = *: ApplyPatchAction
+
+[all.eslint]
+bears = ESLintBear
+default_actions = *: ApplyPatchAction
+
+[all.linelength]
+ignore = generate.js
+bears = LineLengthBear
+
+[all.links]
+bears = InvalidLinkBear
+
+[json]
+files = *.json
+ignore = package-lock.json
+bears = JSONFormatBear
+indent_size = 2
+default_actions = *: ApplyPatchAction
+
+[yaml]
+files = *.yml, .eslintrc
+bears = YAMLLintBear

.eslintrc

@@ -0,0 +1,13 @@
+---
+parserOptions:
+  ecmaVersion: 2017
+plugins:
+  - prettier
+rules:
+  prettier/prettier:
+    - error
+    - singleQuote: true
+      semi: false
+      trailingComma: es5
+      bracketSpacing: true
+      arrowParens: avoid

.travis.yml

@@ -1,13 +1,21 @@
-sudo: false
-language: node_js
+language: python
+python: 3.6
+
+before_install:
+  - nvm install 8
+  - npm install
+  - pip3 install coala-bears
+  - export PATH=$PATH:./node_modules/.bin
+  - export NODE_PATH=$NODE_PATH:./node_modules
 
 script:
+  - coala --non-interactive -V
   - npm run build
 
 deploy:
   provider: pages
   skip_cleanup: true
-  github_token: $GITHUB_TOKEN # Set in travis-ci.org dashboard
+  github_token: $GITHUB_TOKEN
   local_dir: out
-  on:
+  "on":
     branch: master

package.json

@@ -12,5 +12,10 @@
   "dependencies": {
     "mustache": "^2.3.0",
     "node-fetch": "^1.7.3"
+  },
+  "devDependencies": {
+    "eslint": "^4.12.1",
+    "eslint-plugin-prettier": "^2.3.1",
+    "prettier": "^1.9.1"
   }
 }