Refactor UDT decoding
Remove unnecessary blob decoding

Clean up imports

Rename decode to listify
Merge pull request #124 from riptano/user_type_refactoring

Refactor decoding in UDT tests
Expand expected exceptions for unavailability

If the coordinator does not know the nodes are down,
we will instead expect to see a server side timeout,
rather than Unavailable.

Parsing string is redundant