Ability to match request locale and use it for templates - #2019

Looks very good.

I added the tests. I think it's ok but there is a strange behavior I commented above. This language matching concept is not very straightforward for me.

Ok I read through RFC 4647 and actually it's not mandatory that filter returns an ordered list:

If the language priority list (see Section 2.3) contains more than
one range, the content returned is typically ordered in descending
level of preference, but it MAY be unordered, according to the needs
of the application or protocol.

So i read the source of LocaleMatcher found here, and indeed when one of the tags in the priority list is the asterisk (*), it just returns the input list as it is.

just one change and we are ready.