url: format ignores query if it's no object

[ajafff]

• Version: v6.0.0-pre (master)
• Platform: Linux klaus-ThinkPad-T410 4.2.0-34-generic Gitter chat room? #39-Ubuntu SMP Thu Mar 10 22:13:01 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
• Subsystem: url

var assert = require('assert');
var url = require('url');
assert.equal(url.format({pathname:'/foo', query: 'bar=baz'}), '/foo?bar=baz');

results in AssertionError: '?bar=baz' == '/foo?bar=baz'

If search is falsy, query is used. Unfortunately query is only used, if it is an object. Strings are currently ignored.

PR incoming