Index deployed jar asynchronously
Index deployed jar asynchronously

Some users see timeouts when deploying, so we should do less before
returning to the user. One thing we can do is index the jar in another
thread. This will also prevent indexing failures from being reported
to the user, making them think the deploy failed (see #568).

clojars/clojars-web,clojars/clojars-web,ato/clojars-web,tobias/clojars-web,clojars/clojars-web,tobias/clojars-web,ato/clojars-web,tobias/clojars-web