Allow extra fields on a service.

[glenrobson]

It is possible to add the full info.json to a Image server and this is recommended in the thumbnail recipe to enable quick retrieval of thumbnails.

Expected behaviour:

When you pass in a info.json to a service:

service = infoJson
print (service)
service["@type"] = "ImageService2"
body.service = [service]
print (body.service[0])

The first print gives the full info.json

{'tiles': [{'scaleFactors': [32, 16, 8, 4, 2, 1], 'width': 1024, 'height': 1024}], 'protocol': 'http://iiif.io/api/image', 'sizes': [{'width': 126, 'height': 95}, {'width': 252, 'height': 189}, {'width': 504, 'height': 378}, {'width': 1008, 'height': 756}, {'width': 2016, 'height': 1512}, {'width': 4032, 'height': 3024}], 'profile': 'http://iiif.io/api/image/2/level0.json', 'width': 4032, '@id': 'https://iiif-test.github.io/test2/images/IMG_5969', '@context': 'http://iiif.io/api/image/2/context.json', 'height': 3024}

Observed behaviour:

The second print statement gives the fields that are retained in the service:

id=Id(__root__=AnyUrl('https://iiif-test.github.io/test2/images/IMG_5969', scheme='https', host='iiif-test.github.io', tld='io', host_type='domain', path='/test2/images/IMG_5969')) type='ImageService2' profile='http://iiif.io/api/image/2/level0.json' service=None

Only the Id, type and profile are retained.

Potential bug location(s):

Easiest fix is to add:

class Config:
        extra = Extra.allow

To serviceItem and serviceItem1