Updated ``zep``
Updated README.md and TODO.md
Updated docblocks for ``Zepto\Zepto`` and ``Zepto\Router``
Fixed Response header's content-type
Small update to ``WhoopsPlugin``
Renamed ``Zepto\Zepto->container['file_loader']`` to ``content_loader``
Renamed ``Zepto\Zepto::router_setup()`` to ``Zepto\Zepto::setup_router()``
Changed ``Zepto\Zepto::default_config()`` visibility to ``public``
Fixes failing Travis tests, put a hard version number for Pimple