add context parameter to xxxToModel APIs to allow host container to pass in additional context (e.g. session id). This is useful for host containers that override platform.getResourceFromUrl to which this context is passed. The getResourceFromUrl implementation can then use the context, for example, when logging stages of the fetch and make it possible to correlate those log entries.
add host-specific context parameter to platform-specific resource-fetching APIs
add docstrings
Merge pull request #12 from mattoshry/fetch_context

add context parameter to xxxToModel APIs to allow host container to pass...