Allow ids to contain hyphens. Fixes #36.

Previously, a mustache like {{foo-bar}} would generate a
parse error, which was a departure from the behavior of
other Mustache implementations.

spec/qunit_spec.js

@@ -106,6 +106,10 @@ test("functions with context argument", function() {
       "Frank", "functions are called with context arguments");
 });
 
+test("paths with hyphens", function() {
+  shouldCompileTo("{{foo-bar}}", {"foo-bar": "baz"}, "baz", "Paths can contain hyphens (-)");
+});
+
 test("nested paths", function() {
   shouldCompileTo("Goodbye {{alan/expression}} world!", {alan: {expression: "beautiful"}},
                   "Goodbye beautiful world!", "Nested paths access nested objects");