dates are ignored when building query strings

**I'm submitting a bug report**
- **Library Version:**
1.0.0

**Please tell us about your environment:**
- **Operating System:**
Windows 10
- **Node Version:**
5.11.1
- **NPM Version:**
3.10.5
- **JSPM OR Webpack AND Version**
JSPM 0.16.39
- **Browser:**
All probably. Chrome 52.0.2743.116 m (64-bit)
- **Language:**
ESNext

**Current behavior:**
Dates are not made into parameters they are ignored. This is as a result of the `if (typeof (value) === 'object')` check on [line 128](https://github.com/aurelia/path/blob/master/src/index.js#L128) resolving true for dates.

**Expected/desired behavior:**
gist.run is down(??) so I can't show the behaviour currently.
- **What is the expected behavior?**
I believe [line 128](https://github.com/aurelia/path/blob/master/src/index.js#L128) should also check that it is not a date and let it fall through into the [else block](https://github.com/aurelia/path/blob/master/src/index.js#L133) so that the date is present in the query string.
- **What is the motivation / use case for changing the behavior?**
I can't put dates directly in query strings, though I appreciate it's probably wise to format the date explicitly first into a string and will be my local work around/fix.