Middleware backward compatible implementation

[aleferri]

• Removed $pass property on net\Route
• Removed $pass parameter on net\Router::map
• Added $config property on net\Route
• Added $config parameter on net\Router::map
• Made dispatchRoute replaceable by the user
• Added optional Middleware Routing Handler (LayersStack and LayersIterator), in the end the router call the original _dispatchRoute
• In Flight::start check $config['pass_route'] instead of $pass (now it doesn't exists anymore)
• All tests updated to PHPUnit 7
• Bumped required php version from 5.2 to 5.6
• Bumped required phpunit version from 4.8 to 7
• Updated the readme.md to show how to use the new Middleware enabled implementation of routing

[Conver]

I don't really see a reason for this PR, can you clarify why this PR should be merged?

[n0nag0n]

If this is still an issue you'd like to address, go ahead an open up an issue so it can be discussed further.