Lots of changes

First I pulled the code out of the rake task and into it's own class.
Using the latest bing_translate which makes use of the new bing azure api.
Wrote a couple of rspec tests. 
Added a dependency on a gem I just wrote to make it easier to only update new keys for translation. That will save on the number of requests made to bing in case you need to update just a few keys.
Fixed an issue I was having with yaml and utf-8
Added an optional path option for when I don't want it to run on my root en.yml file.

All this started because I wanted a fast and automatic way to generate locales files for simple words and phrases. It scans all the haml files for non scoped keys and adds them to the en_dictionary.yml file. Then i run bing_translate_yaml on it for each language that I need.

source 
https://gist.github.com/KellyMahan/4c471ec96d36cb386fe7

If you want to add that into the project as another rake task I can do so.