Suggested fixes for date sort problem on bibliography and text value attribute

[mguelck]

I've uploaded a patch with suggestions for two fixes:

1. Sort by date does not work properly in bibliography. As discussed
here: http://forums.zotero.org/discussion/9298/apa-6th-new-style/#Item_30

Problem was that the date is handled differently when used as a sort
key. The sort is key calculated from the date but never returned. As a
matter of discussion: I wonder why there is actually a distinction
between regular usage of a date and usage as a sort key. Shouldn't
they be identical as sorting should be comprehensible for the user
(e.g. sort should not consider month if it is not displayed - as it is
the case now with this quick fix)?

2. Value property on the CSL Text entity does not work properly.
Although it is handled, the necessary dataAppended is not set.

Looking forward to you comments on issue no 1.

You can find the patch at: http://groups.google.com/group/zotero-dev/web/bibliography_sort-text_value-csl.js.patch