Added specs for the new Model.update behavior, also added even more spec tests for column id/auto increment/primary key field validating properly. Closes #220 and #799

Added a new functionality to Model.update, it'll now .validate the attribute hash/object before attempting to update all of the records... whoever wants to sign off on this must consider this first:

```
Model.bulkInsert currently has {validate: false} as the default, I decided to make Model.update's {validate} to
be true by default, the logic being that Model.update isn't exactly a bulk method, it's not designed to be
streamlined at all (it's just 1 query as oppose to N queries with bulkInsert). Let me know if you want to change
this OR bulkInsert's)
```