Rearranged how explicit kwargs are passed into queue.enqueue(). Fixes #322
Fix pipeline call.
Fix whitespace.
Reimplement Queue.empty() in a Lua script.

This makes the .empty() function perform all the computing in Redis
itself, rather than in Python.  This is both atomic, and faster.
Add rqinfo -X command.

This can be used to empty the failed queue right from the command line.
Merge pull request #333 from selwin/explicit-args

Rearranged how explicit kwargs are passed into queue.enqueue(). Fixes #322
Merge pull request #334 from nvie/emptying-failed-queue

Emptying failed queue