Sql server compact as biggy backing store, rewritten for happy new API

Hi there!

As I promised I adjusted SqlCe implementation for new API (and fixed some bugs by the way). I tried reuse as much sqlserver's code as works with compact edition. 

Difference are:
 * own Insert() because fetching back auto-pk cannot be done in single command,
 * bulkInserts for both store and documentStore, here I need to reuse connection, because of "open sessions limit"
 * more about you can find in #5 

No changes in core Biggy modules.

Please, let me know what do you think, thanks!