include session events in the export
include transport type & direction
Merge branch 'develop' into feature/issue-851-message-export-session-flags

Conflicts:
	go/conversation/tests.py
restore tests deleted during conflict merge
Merge branch 'feature/issue-851-message-export-session-flags' into develop
Merge branch 'develop' of github.com:praekelt/vumi-go into develop