Update schema for filefort

## Update Asset Creation Schema for Filefort ##

There are 3 methods in the old HttpInvoker ```AssetCreationService``` that are not in the current API.  They are:

1. ```getVersionCount``` -- to get the number of versions of an attachment based on uuid
2. ```getFile``` -- get the file associated with an attachment (in the JSON version this will return just the path to the file)
3. ```getBytes``` -- get the byte content of an attachment

I have created a new interface asset_file.json for these.

Additionally there are 2 asset types "FILE" and "PHOTO" that are used in file fort that are not included in the schema.  I have added these.