Fixing for starting at correct offset for monitored files (Issue #61)

There are two commits here they close issue  #61

https://github.com/jordansissel/lumberjack/issues/61#issuecomment-24119786

The first one 28dc5d4, is a recommit of PR #84.  I think I messed up the PR and it did not merge.

The second commit address the issue that when following more that one file, the registrar file was only the last file.