Misc. updates in response to bulk messaging pull request comments
Update schedule in roadmap
Merge pull request #357 from rapidsms/bulk-api-comments

Misc. updates in response to bulk messaging pull request comments
Merge remote-tracking branch 'remotes/origin/develop' into 342-document-incoming-outgoing-messages

Conflicts:
	rapidsms/messages/base.py
	rapidsms/messages/incoming.py
	rapidsms/messages/outgoing.py