Set user language from browser header if no cookie is available

[Bertware]

The language selection is an additional screen between navigating to irail.be and performing a search. Selecting a language takes almost as long as taking a train, the language selection is intrusive and does not feel really user-friendly

Current situation:

• Visit irail.be for the first time, or with cleared cookies.
• Language selection is shown. The user needs to select a language before he can search for trains.
• User selects language and continues.

Proposed improvement:

• Visit irail.be for the first time, or with cleared cookies.
• Language is deducted from Accept-Language header. If Dutch or French is not found in the header, English is used as fall-back.
• User can instantly search for trains
• (optional) a notification bar is shown asking the user if he wants to change his language. This does not hinder searching for trains

When the user has already visited irail.be, the previous language is used. (This is already the case)