updated package dependencies, implemented "or null" operator for WHERE clauses, added support for auto created/updated timestamp columns

I've updated all the dependencies of FastLegS so that it works correctly with Node 0.6.0+.

I added an "or null" operator for WHERE clauses so you can say things like "value is 0 or null".  I think this is a pretty common use case, and it was impossible to express before.  Example of how it is used:

```
dataLayer.Feed.find(
    {
      "indexed_at.lte.or_null": indexTime
    },
    {
      only: [ 'id' ]
    },
    callback);
```

This will return all rows where the "indexed_at" column is before ```indexTime``` or "indexed_at" is NULL.

My third change is support for automatically setting created and updated time stamps for each row.  You configure them like so:

```
exports.Feed = FastLegS.Base.extend({
  tableName: "feeds",
  primaryKey: "id",
  updateTimestamp: "updated_at",
  createTimestamp: "created_at"
});
```

The column names can be whatever you want, in this example I use the Ruby nomenclature of "updated_at" and "created_at" as the column names.  You don't have to specify both created and updated.  Every time you issue a create() or update() call, the relevant column will be updated (in the case of create(), update is also set to the same time).