Account creation returns accountId as a string.
Remove superfluous 'apiKey paremeter from security.

For most api-key related things it is superfluous and, in fact, simply
overriden by the on provided in the path.
Fix incorrect constraints on deleting API keys.
Improve metadata documentation.
Document the property paramter for metadata.

Also some other miscellany, such as noting the fact the example response
may not exactly match real output (due to feature-lackin').
Made count match total of sub-counts.