run TestReOpen with both poll = true and false

this catches a bug with log rotation when using polling file watcher.
PollingFileWatcher.ChangeEvents must detect file deletion/rename
implement PollingFileWatcher.BlockUntilExists
remove a redundant goroutine
allow compilation on Go1
add change log
Merge pull request #3 from srid/bug99126_rotation_when_polling

Make tail work with file rotation when using polling file watcher