OSMF SVN

Adding a unit test for FacetGroup.

Adding header and ASDocs.

Following up on composite metadata code review feedback.

Remove IMediaTrait.

Adding unit test for CompositeMetadataEvent.

Extending unit tests, and fixing a bug.

Adding null param to URL constructor in unit test.

Extending CompositeMetadata unit tests. Adding null checks to CompositeMetadata.

Removed ID check, as is optional now in newest Manifest Spec.

Disabled parse error test introduced in last checkin.