Updated all instances of home_url() with esc_url()

Updating the rest of the home_url() calls

https://github.com/roots/roots/pull/1066#issuecomment-47315590
Also this inline conditional is ugly as hell. This code should be safe:

```php
<input type="search" value="<?php echo get_search_query(); ?>" name="s" class="search-field form-control" placeholder="<?php _e('Search', 'roots'); ?> <?php bloginfo('name'); ?>">
```

`get_search_query` uses `get_query_var('s')` which uses `$wp_query->get('s')` which returns the default of `''` if its not set. So no reason to wrap it in the `is_search()` conditional.