Fix data race on kevent buffer.

In the BSD implementation of fsnotify, the watcher's kbuf buffers a kevent
between syscall.SetKevent (which prepares the kevent) and syscall.Kevent
(which registers the kevent). The implementation intends to protect access to
kbuf, but fails to do so in addWatch and removeWatch.
This change fixes the data race by allocating a new kevent buffer for every
method invocation.
Merge pull request #98 from tilaks/master

Fix data race on kevent buffer.

Not sure why a mutex doesn't work, but this fix will work.
Re-use WatchFlags method in Watch.
kqueue: fix incorrect mutex used in Close()

identified at https://code.google.com/p/go/issues/detail?id=8282#c5
moving notice to fsnotify/fsnotify
Merge pull request #99 from stuartnelson3/master

Re-use WatchFlags method in Watch.
Merge pull request #100 from gophertown/howeyc_wmut

kqueue: fix incorrect mutex used in Close()
Merge pull request #101 from gophertown/howeyc_moving

moving notice to fsnotify/fsnotify
Changed wording of moving notice
update moving notice to go-fsnotify
Merge pull request #105 from gophertown/moving2

update moving notice to go-fsnotify