activation list should allow server-side filtering by activation type

[rabbah]

When one lists activations today, there is no way to filter on the server side activations that are singleton actions, sequences, or conductor top level invocations. This forces a client to have to scan through many activations to find the ones that it's looking for.

So this issue is to propose and scope filtering activations by some of their annotations on the server side.

[larandersson]

@rabbah I would also propose adding the option of filtering by statusCode. I've already done some experimenting on different options for the view key in CouchDB, and perform combined filtering based on several filters like namespace, name, version, kind and status. However, given the nature of CouchDB, this is not an easy task to solve if you want to filter on several attributes at the same time. It becomes almost impossible if you also want to be able to perform the equivalent of a LIKE filter.