Cassandra client encryption
Optionally enables Cassandra client encryption; Enables encryption
only if the tls stanza in the configuration is present.
Driver behavior is such that at a minimum, you *must* specify a valid
CA cert to enable client encryption. It it acceptable to omit the key
and cert if validation is not being performed, but then *both* must be
omitted. The error message that trickles up from the driver when you
specify a CA but not both a key and cert is descriptive, but omitting
the CA when either a key or cert has been specified results in a
confusing error (connection reset by peer). As a result, config
validation was added to address this case.
cassandra_schema.cql ...: Use correct comment syntax
storage_test.go ........: Fail tests fast if setup() fails
storage_test.go ........: Execute TestSetGetDelete steps as subtests (cleaner
code, cleaner results output)