[conformal/btcd] 766aae: Add rolling log file.

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcd
  Commit: 766aae5a728e2ec53af43e4e65cf87c7e875e20b
      
https://github.com/conformal/btcd/commit/766aae5a728e2ec53af43e4e65cf87c7e875e20b
  Author: Dave Collins <da...@conformal.com>
  Date:   2013-11-25 (Mon, 25 Nov 2013)

  Changed paths:
    M config.go
    M log.go

  Log Message:
  -----------
  Add rolling log file.

This commit modifies the logging to also log all output to a rolling log
file in the btcd home directory under the logs folder.  It uses a maximum
size of 10MB per log file and a max rotation size of 3.  This means the
log files will not exceed 30 megabytes.