cannot run BasicTimeSeries with cassandra < 3

[rustyrazorblade]

Since we added the deletion flag it hasn't been possible to run the time series workload with version 2.x, because it throws an exception when trying to prepare the statement. We put a guard in front of the prepare query to block it, but that breaks the older versions that don't support the range delete.

We need to fix this before the next release. We either need to refactor how prepare is handled or delay the exception till later.