Report :num-control-busses in server-info
Prefer 'buses' over 'busses' to avoid confusion and typos...

Either one is fine but we should pick one. Searching for "audio buses" and
'site:doc.sccode.org "buses"' yeilded more results than their "ss" counterparts,
so I chose "buses".
Make it easier to run 'core' tests using test selectors (requires lein 2)...

Use `lein test overtone.smoke-test :core` to skip gui tests and test requiring
additional hardware.
Merge branch 'master' of github.com:overtone/overtone

* 'master' of github.com:overtone/overtone:
  Rename apply-at to apply-by and implement apply-at to apply the fn at the specified time, not before it.