Merge pull request #12 from adlnet/master

update garemoko master to adlnet
Querying voided statements
tiny typo
rewrite of 4.1.2 Actor

plus some changes to identified group property table
forgot change two words
and a typo...
Clean up "actor" vs. "agent/group" usage in statement querying

* Remove "Statement Object (JSON)" from type, no related information in
  "description" column
Put back "(JSON)" in type column for statement querying
Updated rewrite of 4.1.2 Actor

based on Andrew's and Russel's review comments. Thanks.
Removed 'authoritative' flag

Shouldn't be controversial, I think we talked about removing this in 0.95 but just forgot to.

For those new to the discussion: this is a holdover from when the LRS was "smarter" than it is now -- we've decided it's up to systems reading statement to decide how to weigh statements.
* Renamed sha-2 and content-Type properties to sha2 and contentType for easier reference as properties
(many languages don't like - in property names)

* Added clarifying requirements
* Added requirement to include hash in each part's header, so receiver doesn't
have to guess which hash length to use when verifying

* Added an example
minor clarification:
"only send one copy" language only applies within a single message
Added flag to include/exclude attachments when retreiving statements
(trivial) updated example hash

Hash in the example was calculated improperly, updated with correct hash.
Clarification

The multipart attachment format is to be used in responses when attachments are requested even if there are no attachments.