Remove locking and tx around promotion, and serialize the update
Remove locking and tx around promotion, and serialize the update

Since artifacts can no longer be redeployed and we're serializing
database writes, we don't need the tx and locking around promotion.

beppu/clojars-web,clojars/clojars-web,technomancy/clojars-web,leonid-shevtsov/clojars-web,clojars/clojars-web,tobias/clojars-web,tobias/clojars-web,nberger/clojars-web,tobias/clojars-web,thiagofm/clojars-web,xeqi/clojars-web,codonnell/clojars-web,codonnell/clojars-web,xeqi/clojars-web,technomancy/clojars-web,dotemacs/clojars-web,ato/clojars-web,dotemacs/clojars-web,ato/clojars-web,nberger/clojars-web,clojars/clojars-web