Ensure frames don't share go-pilosa StatusChannels

[travisturner]

When providing a gopilosa.ImportStatusUpdate to pdk.SetupPilosa() via:

    statusChan := make(chan gopilosa.ImportStatusUpdate, 1000)

    indexer, err := pdk.SetupPilosa(m.PilosaHosts, m.Index, frames,
        gopilosa.OptImportStatusChannel(statusChan))

and when multiple frames are passed in to frames, then two problems occur:

1. multiple frames share the same status channel
2. upon import completion, all frames try to close the channel, which causes a panic

I'm still not sure if it's best to handle this in PDK or go-pilosa, but it seems we need a way to provide multiple channels (one per frame) for status updates. An alternative would be to modify go-pilosa such that the single status channel is aware of index/frame, and therefore supports multiple frames.

This needs more investigation.