Add new instance types to Elastic Bamboo

There are several EC2 instance types that aren't supported by Elastic Bamboo, including the very highest performance instance types, which are great when you want to throw money at a build to make it go faster.

The list I see in the drop down in Bamboo 4.1 OnDemand is missing the following instance types:

Medium (m1.medium)
Cluster Compute Eight Extra Large (cc2.8xlarge)
High I/O Quadruple Extra Large (hi1.4xlarge)

The last two especially seem important, as they provide a way to pay for more performance that you can't get with any other instance types. (Users who need medium can pay for large, and spot prices aren't that different right now.)