Field Cleanup, First Pass

Fields has a lot of the normal problems.
1) Can not extend it easily.
2) Bunch of classes all shoved into a single file.
3) Its factory method is non-obvious as to how it works.

So to get the ball moving:

1) A directory named "fields" will be created.
2) In it .cc and .h files will be created for each class. Blob will be named blob.cc/.h as an example. Proper include headers will be used.
3) The main field.cc will be left as it is at this point. Once we have part two done, we refactor field.cc to give us the ability to add in additional classes.
4) Final bits of 24bit INT type to be removed.

Additional Options:
1) We had a native UUID type.
2) We take the patch for IPV6 type and add it.

It would be really nice to see that big matrix of conversions removed from the top of field.cc. AKA lets make it easy to add new types, and to do that... we have to rethink some things.