Merge pull request #205 from alxhub/master-v0.2

Refactor and rename multiplexer_test to handler_test and include in all_tests.dart.
isPrimary now takes an AssetId instead of an Asset.
Merge pull request #206 from alxhub/fix-barback

Barback version update changed isPrimary() - now takes an AssetId instead of an Asset
Merge remote-tracking branch 'upstream/master-v0.2' into master-v0.2
Addendum tests passing.