Delete download and local docset after deploying a documentation

[kylef]

These are starting to build-up:

$ ls -l /Users/orta/cocoadocs.org/activity/download | wc
    1457   13106   90205
$ ls -l /Users/orta/cocoadocs.org/activity/docsets | wc
    5802   52211  357080

1457 directories of download (+ versions inside) and 5802 for dockets.

[orta]

odd, I'm pretty sure I had code in for deleting these.

[kylef]

I think it may have been broken due to separation between cocoadocs.rb and server.rb. Haven't fully checked yet.