update readme

1.0.8

handle /collection.json and /manifest.json suffixes as per the iiif fixtures

1.0.7

added range and layer models

1.0.6

changed resource and service property names from plural to singular to be in line with the spec

1.0.5

ensures that manifests have a _id

1.0.4

removed url and app_url artifacts from manifest model

adds stub for testing collection fetch() from endpoint

adds stub for testing collection fetch() from endpoint

document fetch()

1.0.3