Batch job support

[aclavio]

Currently a state conductor "job" or "execution" is scoped to a single URI. However it may be desirable for this execution to contain a batch of URIs. This implies that each document in these batches will move through the applicable states as a group, and will fail or commit each transaction together. The action and condition modules will need to accept or anticipate the possibility of processing multiple documents at once.

[aclavio]

One possible implementation involves removing the "uri" from the job document's root level, and simply reloading into the job's context as a "uri" parameter. Then batches could utilize a "uris"/"batch" array parameter in the context instead. This should work in the case where no uri is passed at all (as in the case of "periodic" flows).

The action modules' "performAction" and condition modules' "checkCondition" function signature would need to be changed; and implementors would need to expect the relevant values to be present in the passed context.

[freshie]

I think removing the URI makes sense.

I think we could use the context to put data in there.

The data would change depending on the type of context.

we'd want it to be backwords compatible