users should be able to add/delete pieces when signed in with their own wallet

[SgtPooki]

taken from filecoin-project/filecoin-pin#58

[BigLep]

I think we need to make some product decisions about how much functionality we want to bring to the "quick getting started flow" that this repo is focused on now vs. building it into more of a webui/gui/management console for filecoin pin as was originally discussed in filecoin-project/filecoin-pin#74

We'll engage on this post GA. For now I have marked this with the MX milestone.