Patch current Chosen with some code from 0.9.9

Let's add support for the these options:
# placeholder_text_multiple: defaults to "Select Some Options"
# placeholder_text_single: defaults to "Select an Option"

These options are the same of newer version of Chosen: if we'll upgrade
Chosen we won't have to patch it again.
Translate some strings for Chosen

Introduce a new ccmi18n_chosen JavaScript object that contains translated
strings for Chosen (it can be used as the option parameter when
instantiating Chosen).
Add a description to a translatable text
Localize Chosen in File manager
Localize Chosen in Search Users
Localize Chosen in Bulk Group Add
Localize Chosen in Bulk Group Remove
fixing area design issue
Merge branch 'translate-chosen-v2' of https://github.com/mlocati/concrete5 into mlocati-translate-chosen-v2

Conflicts:
	web/concrete/js/ccm_app/ui.js
Chosen localize