Allow the use of double quotes to avoid escaping

See https://github.com/hypothesis/client/pull/32#discussion_r70957311

.eslintrc

@@ -43,7 +43,7 @@
     ],
     "no-useless-concat": "error",
     "one-var-declaration-per-line": ["error", "always"],
-    "quotes": ["error", "single"],
+    "quotes": ["error", "single", {"avoidEscape": true}],
     "semi": "error",
     "strict": ["error", "safe"],
   },

h/static/scripts/test/groups-test.js

@@ -85,7 +85,7 @@ describe('groups', function() {
       assert.equal(group.id, 'id2');
     });
 
-    it('returns null if the group doesn\'t exist', function() {
+    it("returns null if the group doesn't exist", function() {
       var group = service().get('foobar');
 
       assert.isNull(group);