Clean up vbucket deletion logic
Clean up vbucket deletion logic

We used to set to dead and delete on separate passes. There is no need
to do that. I also made it easier to read.

I'd thought there was a way for vbuckets to "leak" through in pending
state, but it turns out they couldn't.

Change-Id: I760cdcb8a8633e3e4f95afbcd5fc8940045fb535
Reviewed-on: http://review.membase.org/3350
Reviewed-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>
Tested-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>

mschoch/ns_server,vzasade/ns_server,vzasade/ns_server,ceejatec/ns_server,ceejatec/ns_server,membase/ns_server,t3rm1n4l/ns_server,vzasade/ns_server,ceejatec/ns_server,membase/ns_server,pavel-blagodov/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,pavel-blagodov/ns_server,nimishzynga/ns_server,membase/ns_server,daverigby/ns_server,membase/ns_server,mschoch/ns_server,ceejatec/ns_server,daverigby/ns_server,mschoch/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,pavel-blagodov/ns_server,daverigby/ns_server,pavel-blagodov/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,mschoch/ns_server,nimishzynga/ns_server,membase/ns_server,daverigby/ns_server,vzasade/ns_server,nimishzynga/ns_server,membase/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,daverigby/ns_server