Automatic hostname route adaptation 

## Problem
In situations where Hostname route is being utilized, for example, in case of a website: *www.example.com* which also have some pages on a separate subdomain: *blog.example.com*, routes definition might look like:
```php
//...
'router' => array(
    'routes' => array(
        'blog' => array(
            'type' => 'hostname',
            'options' => array(
                'route' => 'blog.example.com',
                'defaults' => array(
                    'controller' => 'Application\Controller\BlogController',
                    'action' => 'index',
                ),
            ),
            'may_terminate' => true,
            'child_routes' => array(
                'post' => array(
                    'type' => 'segment',
                    'options' => array(
                        'route' => '/[:slug]',
                        'constraints' => array(
                            'slug' => '[a-zA-Z0-9_-]+'
                        ),
                        'defaults' => array(
                            'action' => 'view'
                        )
                    )
                )
            )
        ),
        'user' => array(
            'may_terminate' => false,
            'type' => 'literal',
            'options' => array(
                'route'    => '/user',
                'defaults' => array(
                    'controller' => 'Application\Controller\User',
                ),
            ),
            'child_routes' => array(
                'view' => array(
                    'type' => 'segment',
                    'options' => array(
                        'route' => '/view[/:id]',
                        'constraints' => array(
                            'id' => '\d+'
                        ),
                        'defaults' => array(
                            'action' => 'view',
                        ),
                    ),
                ),
                'edit' => array(
                    'type' => 'segment',
                    'options' => array(
                        'route' => '/edit[/:id]',
                        'constraints' => array(
                            'id' => '\d+'
                        ),
                        'defaults' => array(
                            'action' => 'edit',
                        ),
                    ),
                ),
            ),
        )
    ),
),
//...
```
The problem occurs when URL for the ```user/view``` route is assembled on some blog page, for example:
```php
echo $this->url('user/view', array('id' => 1));
```
That URL will point to the *blog.example.com*, even if ```force_canonical``` options is supplied.

## Solution
In this situations, Router component should respond in such way that assembled URLs always point to the appropriate hostname. This can be achieved by inflecting all the other non-hostname routes into **Chain** routes, consisting of a default hostname route and the inflecting route itself.

This improvement does just that, by automating that inflection of non-hostname routes. Thereby, developer is required to supply default hostname route definition along with other ```'router'``` options, for example:
```php
'router' => array(
    'default_hostname_route' => array(
        'type' => 'hostname',
        'options' => array(
            'route' => 'www.example.com',
        ),
    ),
    'routes' => array(
        //route definitions...
    ),
),
```
As a result, assembling of a ```user/view``` route from the above example:
```php
echo $this->url('user/view', array('id' => 1));
```
... would always result in: *http://www.example.com/user/1*, regardless of a subdomain on which it is being assembled.