Getting started on the executable

Hey, it's working! Sweet!

Lots of cleanup to do on these ideas, but close enough for a working
proof of concept :)
Huzzah! autoscaling works!
Initial pass at logging

& other minor changes
extract SignalHandler and Logger into their own files
WorkerGroups shouldn't be in the nitpicky business of queues

TODO: finish tests for the new classes
oops. that should be require, not include
Queue/QueueGroup cleanup and code improvements

* Make QueueGroup enumerable
* eschew if/then where possible
Code beautyfication
missed one
a teensy bit more cleanup
Return to 100% coverage
Bump version in prep for merge
Merge pull request #5 from wideopenspaces/add_bin

Add executable (WIP) and other improvements.