Some error-checking was omitted.
Specifically, the cloudTrailSetLogging call in the Create function was
ignoring the return and cloudTrailGetLoggingStatus could crash on a
nil-dereference during the return. Fixed both.
Fixed some needless casting in cloudTrailGetLoggingStatus.
Clarified error message in acceptance tests.
Removed needless option from example in docs.
The default for `enable_logging`, which defines whether CloudTrail
actually logs events was originally written as defaulting to `false`,
since that's how AWS creates trails.
`true` is likely a better default for Terraform users.
Changed the default and updated the docs.
Changed the acceptance tests to verify new default behavior.
Ninir