Fixed clobbering the lodash template settings

refs: https://github.com/lodash/lodash/issues/705

- Was seeing unexpected token = errors when using lodash templates in Ghost
- This is because we're setting template settings globally in this dependency and it affects every other user of lodash
- Using runInContext keeps this templateSettings change local to this lib
- Test proves that after requiring limits we can require lodash and have the default values again

ghost/limit-service/lib/limit.js

@@ -1,6 +1,7 @@
 const errors = require('@tryghost/errors');
-const _ = require('lodash');
 
+// run in context allows us to change the templateSettings without causing havoc
+const _ = require('lodash').runInContext();
 _.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
 
 class Limit {

ghost/limit-service/test/hello.test.js

@@ -1,10 +0,0 @@
-// Switch these lines once there are useful utils
-// const testUtils = require('./utils');
-require('./utils');
-
-describe('Hello world', function () {
-    it('Runs a test', function () {
-        // TODO: Write me!
-        'hello'.should.eql('hello');
-    });
-});

ghost/limit-service/test/template.test.js

@@ -0,0 +1,12 @@
+// Switch these lines once there are useful utils
+// const testUtils = require('./utils');
+require('./utils');
+
+describe('Lodash Template', function () {
+    it('Does not get clobbered by this lib', function () {
+        require('../lib/limit');
+        let _ = require('lodash');
+
+        _.templateSettings.interpolate.should.eql(/<%=([\s\S]+?)%>/g);
+    });
+});