[switcher] Add option for browser-lang order

[lunetics]

we could also render the locale list depending on the accept language specification

example:

Accept-language', 'fr-FR,fr;q=0.1,en-US;q=0.6,en;q=0.4

and allowed locales:

allowed_locales:
    - en
    - de
    - fr

output of the switcher list:

• fr
• en
• de