chore: configure prettier and eslint

- add prettier to do formatting
- add eslint-config-prettier to
  disable rules conflicting with prettier
- remove eslint from grunt workflow
- use lint-stage to lint and format
  on precommit
- use eslint and prettier in travis directly
- remove rules that are already part of
  the "recommended" ruleset

That rational is that eslint and prettier should be run in
Travis-CI, on commit and as IDE integration (highlighting
errors directlry). They don't need to be run along with
test-cases. Getting linting errors when running the tests
because of missing semicolons is just annoying, but doesn't
help the overall code-quality.

spec/.eslintrc

@@ -1,7 +1,8 @@
 {
   "extends": [
     "../.eslintrc.js",
-    "plugin:es5/no-es2015"
+    "plugin:es5/no-es2015",
+    "prettier"
   ],
   "plugins": [
     "es5"
@@ -43,4 +44,4 @@
     "no-var": "off",
     "dot-notation": "off"
   }
-}
+}

spec/amd-runtime.html

@@ -26,8 +26,8 @@
       window.expect = chai.expect;
       mocha.setup('bdd');
     </script>
-    <script src="/spec/env/json2.js"></script>
-    <script src="/spec/env/require.js"></script>
+    <script src="/spec/vendor/json2.js"></script>
+    <script src="/spec/vendor/require.js"></script>
 
     <script src="/spec/env/common.js"></script>
     <script>

spec/amd.html

@@ -27,8 +27,8 @@
       window.expect = chai.expect;
       mocha.setup('bdd');
     </script>
-    <script src="/spec/env/json2.js"></script>
-    <script src="/spec/env/require.js"></script>
+    <script src="/spec/vendor/json2.js"></script>
+    <script src="/spec/vendor/require.js"></script>
 
     <script src="/spec/env/common.js"></script>
     <script>

spec/index.html

@@ -28,7 +28,7 @@
       mocha.setup('bdd');
     </script>
     <script src="/dist/handlebars.js"></script>
-    <script src="/spec/env/json2.js"></script>
+    <script src="/spec/vendor/json2.js"></script>
     <script src="/spec/env/common.js"></script>
     <script>
       var CompilerContext = {

spec/umd-runtime.html

@@ -26,8 +26,8 @@
       window.expect = chai.expect;
       mocha.setup('bdd');
     </script>
-    <script src="/spec/env/json2.js"></script>
-    <script src="/spec/env/require.js"></script>
+    <script src="/spec/vendor/json2.js"></script>
+    <script src="/spec/vendor/require.js"></script>
 
     <script src="/spec/env/common.js"></script>
     <script>

spec/umd.html

@@ -27,8 +27,8 @@
       window.expect = chai.expect;
       mocha.setup('bdd');
     </script>
-    <script src="/spec/env/json2.js"></script>
-    <script src="/spec/env/require.js"></script>
+    <script src="/spec/vendor/json2.js"></script>
+    <script src="/spec/vendor/require.js"></script>
 
     <script src="/spec/env/common.js"></script>
     <script>