store a "location" property on the context object

cc @tmeasday

This location object will be a parsed url like
Iron.Url.parse('/some/url');

It will be the location at the time the dispatch occurs. So it's
possible that downstream middleware stacks can mutate this property as
the context moves through different middleware stacks.
fix Handler to accept a regular expression path
fix test() method to properly handle HTTP methods
bump version to 1.0.0-pre1
bump version to 1.0.0-pre2
bump versions to pre3 and remove versions.json