Convert chat translation to third party paid translation services

Google is discontinuing the free translation service. The details of the new paid service are available now:

http://code.google.com/apis/language/translate/v2/getting_started.html

We should convert our usage to the paid service, allowing the user to configure the service and any credential or key needed to use the service.

Investigate the complexity of supporting both Google and Bing translation services (the design should allow for others to be added, but let's limit ourselves to these to for now).

1. Update the Chat preferences to include:
   1. A way to select which service to use
   2. A link to the pricing and account creation information (for Google, that's http://code.google.com/apis/language/translate/v2/pricing.html)
   3. A way to enter the API key obtained the user from the service
2. Provide a user interface somewhere to see how much the service has been used:
   1. The total number of characters that have been sent for translation (Google pricing is in millions of characters)
   2. A separate display of a counter of characters sent since the last time it was reset, along with the date when it was last reset (like a trip odometer)
   3. A link to the billing page (which should show only when a service has been selected and a key has been entered) (for Google: https://code.google.com/apis/console#:billing)

Extra credit idea to consider:

At present, the translation preferences allow you to specify only one language; the source language is autodetected. Might it be worthwhile to have both be specified (my language & then for any given chat, either autodetect or specify the other language).