Refactor Test suite names to better illustrate intent

[ncatelli]

Example:

=== RUN   TestDriverRollbackMethodShould/pop_the_most_recent_revision_off_of_the_in_memory_state
--- PASS: TestDriverRollbackMethodShould (0.00s)
    --- PASS: TestDriverRollbackMethodShould/pop_the_most_recent_revision_off_of_the_in_memory_state (0.00s)
=== RUN   TestDriverStateMethodShould
=== RUN   TestDriverStateMethodShould/return_latest_revision_when_revision_state_exists
=== RUN   TestDriverStateMethodShould/return_nil_when_revision_state_doesn't_exist
--- PASS: TestDriverStateMethodShould (0.00s)
    --- PASS: TestDriverStateMethodShould/return_latest_revision_when_revision_state_exists (0.00s)
    --- PASS: TestDriverStateMethodShould/return_nil_when_revision_state_doesn't_exist (0.00s)