Merge pull request #8 from adlnet/master

Sync up!
4.1.5 Score
clarify "ids" statement query format

* replace agent with "agent and groups"
* note that for anonymous groups, each member must be included
Merge remote branch 'upstream/master' into andy

Conflicts:
	xAPI.md
Merge pull request #257 from bscSCORM/ids

clarify "ids" statement query format
Merge pull request #9 from bscSCORM/andy

Fixed merge conflicts
Merge pull request #258 from andyjohnson/master

Clarify Section 4.1.5