Remove the foreign link description and forward to the foreign error

[cramertj]

Fix #15

[brson]

Thanks @cramertj. I posted a question to the urlo error-chain thread asking what people thought of the breakage caused by removing this.

As I was writing it though my brain was telling me, 'come on just do it backwards compatibly'. How hard do you think it would be to make the macro optionally parse that string and just discard it?

[cramertj]

Just discard it? It wouldn't be hard at all, but it would prevent users from discovering the change to the underlying library functionality. Users could potentially continue working with the faulty assumption that their display string was being used, which I think is worse than the minimal API breakage. Considering they're already bumping the version in order for the API change to occur, it doesn't seem like too much to ask that they just delete the description string.

[brson]

Rebased and merged.