Internal references are now adjusted on check in to be relative to the project directory. These references are then deemed to be valid.
Paths are now stored relative. Absolute paths are constructed when the path/directory attribute is requested. Every appropriate asset also has a relative_path/directory attribute that can be used when constructing relative child paths/directories. Closes #30
Fixed a bug with publishing assets using the new relative paths system. Also fixed a bug with maya deferred reference loading. Internal reference can be detected, but that cannot be chagned. Thus internal references should always be created relative in the maya file. If they're not then the system will detect that and notify the user, but it won't be able to change it.