[#7042] Add activity tags

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>
[#7042] Add tags to json feed

Cleaned up inconsistency in use of related_nodes vs target

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>
[#7042] Fix test

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>
[#7042] Add tags to create_activity assertion

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>
[#7042] Bump ActivityStream to version 0.2.0 for tag feature

Signed-off-by: Cory Johns <cjohns@slashdotmedia.com>