Months and days translated

Hi,

First of all, sorry for my bad english.

I have removed nl and tr language files to add new entries in en language file and add fr language file.
The format to explain a relative date should depends from a language, according to me, ie in french '42 minutes ago' become 'there is 42 minutes', the suffix change the place with some language.

I have rename ago method to diffForHumans because some case it returns 'ago', some case 'from now', it's more a difference betwin two dates.
I move predefined formats to language files because there are language dependant
I modify the code to use Config::get('app.timezone') as default time zone if none was given.

Hope this helps.

Regards