New Formula: Kestrel 2.4.1

Kestrel is a java-based simple queue system that speaks memcache protocol. This is the standalone version that does not require scala or sbt, just java.

See http://robey.github.com/kestrel/ and https://github.com/robey/kestrel

Continues the work of https://github.com/mxcl/homebrew/pull/9020