Chosen localized (but not upgraded)

Let's localize Chosen...
Unlike #1012, now I patched the current version of Chosen (0.9.5) with some code from the latest Chosen version (1.0).
In particular the optional `option` parameter now allows also to specify the texts for "Select Some Options" and "Select an Option".
If those properties of `option` (and even `option` itself) are optional: if they are not specified we fall back to the English texts.

Bugtracker: http://www.concrete5.org/developers/bugs/5-6-2-1/non-translated-value-select-some-options/