Rename tickbox "Show unmapped"

[pwalczysko]

In order to give some lead about where to start to the first time user, rename the "Show unmapped" tickbox to "Create Tag". No need to be too precise, this should just give a lead to a first-timer, who needs to start somewhere. Two things are needed.

1. Rename it
2. Make it bigger/bolder

[pwalczysko]

cc @will-moore

[dpwrussell]

I think I might call it "Show All Potential Tags" instead of "Create Tags". I just don't feel that "Create Tags" makes sense as that suggests that by clicking this, tags will be created which they will not unless tokens are then mapped.

[pwalczysko]

Makes sense to me.