Simplify content type shown in dir lists

tests/unit/utils/simple-content-type-test.js

@@ -0,0 +1,11 @@
+import simpleContentType from 'inspektor/utils/simple-content-type';
+import { module, test } from 'qunit';
+
+module('Unit | Utility | simple content type');
+
+test('it removes the charset portion', function(assert) {
+  let type = 'application/json; charset=UTF-8';
+  let result = simpleContentType(type);
+
+  assert.equal(result, 'application/json');
+});