Improve `--describe` output

[Michael Solomon]

Can you please ellaborate about each property?
For example:

➜  meetings-service git:(Michael/rank/SCPJM-115) ✗ ./tm.py --describe Datastore
The following properties are available for Datastore
	OS
	authenticatesDestination
	authenticatesSource
	authenticationScheme
	authorizesSource
	check
	definesConnectionTimeout
	description
	dfd
	handlesInterruptions
	handlesResources
	hasAccessControl
	hasWriteAccess
	implementsAuthenticationScheme
	implementsNonce
	inBoundary
	inScope
	isAdmin
	isEncrypted
	isHardened
	isResilient
	isSQL
	isShared
	name
	onAWS
	onRDS
	providesConfidentiality
	providesIntegrity
	storesLogData
	storesPII
	storesSensitiveData

What is the difference between storesSensitiveData and storesPII?
onRDS include Aurora?
What's authenticatesDestination/authenticatesSource?
What's the expected values (enum) for authenticationScheme?
And so on
Thanks

[Michael Solomon]

Duplicates of #28