Save exceptions to redis and add better error handling to retrieve the gem specification

Easy debugging for developers

- Allow you to save the exception to a redis list with `push_exception`, you have to manually use it in your rescue block. I'll check with lita authors to see if we can add a cleaner way to catch all the exceptions.
- The exception queue is limited to 20 items.
- You can `pop` the exception from the queue with the command `why computers so bad?`

Fixes #3
ruby should work, I was trying to understand why it didnt work on the linux box.
I was before learning that jruby-1.7.16 wasn't installed.

I'll revert it.