Make uri format configurable
Add actions for yanking id/uri

I think I'll have use for this functionality later.
Minor code clean up
Add a simple action to view a task

This is probably overly simply. It will be helpful to create a buffer and have
some useful keybindings and such but that is in the future. This will work for
me for now.
Move toward a more standard unite interface

I was using taskwarrior:tags to list tags. It is more standard to use
taskwarrior/tags to do things like this. So I'm moving toward this sort of
interface for tags, projects and the annotation view. Also, I've fixed an issue
in the taskwarrior_cmd kind.