entitlements scheme proposal

add EntitlementsTest
record entitlement context for REST web requests, and log more info of web requests
add AcmeEntitlementManagerTest
add isEntitled check to ApplicationResource and EntityResource
add unauthorized to WebResourceUtils
add FROM_ENTITY function to EntityTransformer
add EntitlementPredicates
address review comments for #23
rename hasEntitlementClass to isEntitled
This closes #23