Multibyte PagePath (URL) support

concrete5 Japan team is taking a look at multibyte issues now.

Multibyte URL is very important to us
Therefore, we have made the pull request to meet the followings:
 
1. Sanitization.

We can use Japanese (and other multibyte characters) for URL slug, but there is no sanitization on both way (enter and output). What's your plan in the future?

2. Decode page path

We need to decode the page path URL at Request class in order to be able to use multibyte characters. Otherwise, it would return 404. Can we do it?

3. When printing out the page path in <a>, we need to encode the page path.

4. Are you still planning to use PagePath object when handling Page object? Or getCollectionPath() would be obsolete?