[FIX] web_calendar: display view's @string in quick create dialog

The quick create popup tried to look up the parent's .string and
.name (or the parent's field_widget's) *but* the calendar view didn't
have a .string, and its .name gave priority to the view's name (as
returned by fields_view_get) as opposed to its @string.

Store the view arch's @string to CalendarView#string, so the quick
create dialog can find and use it.

addons/web_calendar/static/src/js/web_calendar.js

@@ -144,6 +144,7 @@ openerp.web_calendar = function(instance) {
             this.$el.addClass(attrs['class']);
 
             this.name = fv.name || attrs.string;
+            this.string = attrs.string || fv.name;
             this.view_id = fv.view_id;
 
             this.mode = attrs.mode;                 // one of month, week or day