[Delivers #43560241 #43560243 #43560261 #43560263] List Volume Types, Describe Volume Type and Test Coverage for both

**Summary**
Added two new methods to list volume types and view details of a particular volume type

**Testing**
Added two integration tests to exercise the new methods and added the two tests to the CloudBlockStorageFull ordered test to ensure full test coverage of the methods.

Pivotal Stories:
https://www.pivotaltracker.com/story/show/43560241
https://www.pivotaltracker.com/story/show/43560243
https://www.pivotaltracker.com/story/show/43560261
https://www.pivotaltracker.com/story/show/43560263