Mako's access pattern should be uniformly random across all keys in FDB

When `mako` is configured to 'get' keys it is only able to 'get' keys that it created with the 'build' command, and is not capable of getting keys it inserted with random names as it does when instructed with `-x 'g8ui'`. Thus gets and updates affect only a certain portion of keys which is undesirable for benchmarking purposes.

This issue can be closed when `mako`'s access pattern is uniformly random across the set of keys in fdb, not just those inserted with the 'build' command.

Proposed Solution:
Mako should insert keys with a deterministic naming scheme, something simple like `makoiXXXXXX` where X is a number starting at 0 and incremented to the current number of inserts. This number can be hashed to ensure the key names are not sequential. Then `mako` can easily access random keys within this range and the range it inserted in the 'build' phase.