WebLink Integration

Added WebLink object type which can be retrieved with the "web_link" parameter for getAccountTree.'
Using the new type in Box for delete and move will allow web_link objects to be deleted or moved to new folders respectively.
Added a status of the error: trying to overwrite a deleted file.
Merge pull request #8 from box/WebLinkIntegration

WebLink Integration
Added Error Codes

Added a few error codes developers can handle in their applications.
Add get_item_roles_for_item.
Add ability to add custom query parameters to all Box API requests.
Fixed invalid file name string when renaming. Previous name missing an underscore.
Added additional params for getAccountTree: show_path_ids, show_path_names.
Merge remote-tracking branch 'box/master'