[conformal/btcws] 0e8cbf: Replace Error with Errorf, found by go vet.

[Josh Rickmar]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcws
  Commit: 0e8cbf71e8e54f4ae5652b83679738424db7d1c5
      
https://github.com/conformal/btcws/commit/0e8cbf71e8e54f4ae5652b83679738424db7d1c5
  Author: Josh Rickmar <jr...@conformal.com>
  Date:   2014-02-04 (Tue, 04 Feb 2014)

  Changed paths:
    M notifications_test.go

  Log Message:
  -----------
  Replace Error with Errorf, found by go vet.