[changed] Use empty bracket notation for arrays

Query strings use empty brackets for encoding arrays, which has
the widest range of support among server-side frameworks.

Fixes remix-run#901
Fixes remix-run#939

May have something to do with remix-run#715

modules/PathUtils.js

@@ -146,7 +146,7 @@ var PathUtils = {
     if (existingQuery)
       query = query ? merge(existingQuery, query) : existingQuery;
 
-    var queryString = qs.stringify(query, { indices: false });
+    var queryString = qs.stringify(query, { arrayFormat: 'brackets' });
 
     if (queryString)
       return PathUtils.withoutQuery(path) + '?' + queryString;

modules/__tests__/PathUtils-test.js

@@ -316,10 +316,10 @@ describe('PathUtils.withQuery', function () {
   });
 
   it('merges two query strings', function () {
-    expect(PathUtils.withQuery('/path?a=b', { c: [ 'd', 'e' ] })).toEqual('/path?a=b&c=d&c=e');
+    expect(PathUtils.withQuery('/path?a=b', { c: [ 'd', 'e' ] })).toEqual('/path?a=b&c%5B%5D=d&c%5B%5D=e');
   });
 
   it('handles special characters', function () {
-    expect(PathUtils.withQuery('/path?a=b', { c: [ 'd#e', 'f&a=i#j+k' ] })).toEqual('/path?a=b&c=d%23e&c=f%26a%3Di%23j%2Bk');
+    expect(PathUtils.withQuery('/path?a=b', { c: [ 'd#e', 'f&a=i#j+k' ] })).toEqual('/path?a=b&c%5B%5D=d%23e&c%5B%5D=f%26a%3Di%23j%2Bk');
   });
 });

package.json

@@ -46,7 +46,7 @@
     "react": "0.12.x"
   },
   "dependencies": {
-    "qs": "2.3.3"
+    "qs": "2.4.1"
   },
   "tags": [
     "react",