support for templated static fixtures

[arjunballa]

• all test cases pass
• also added documentation

// Now Templated urls can also be used with templated static fixtures.

$.fixture({
type : "GET",
url : "/todos/{id}",
}, "//jquery/dom/fixture/fixtures/test.{id}.json");

// below ajax call looks for jquery/dom/fixture/fixtures/test.911.json fixture
$.get("/todo/911", function(data) {
// data is json object constructed from //jquery/dom/fixture/fixtures/test.911.json fixture
}, "json");