Custom Publish Headers

[jonnii]

Messages can now be adorned with an IHeaders interface which gives each
message you publish access to the headers collection on the default
properties.

Todo

• Make this a publisher configuration too, so that you don't need to mark up your objects with interfaces.

This will close #28

/cc @tanir @cocowalla

[jonnii]

@tanir is this something you're still interested in?

[tanir]

Yes I am interesting in adding some feature, that allows to set a custom header when publish a message.

[jonnii]

@tanir, take a look at the change in this PR, is this the kind of thing you're thinking?

[jonnii]

@tanir this is ready to go. you can add an interface to a message to get custom headers, or supply a publisher strategy for setting headers. Let me know if this is what you had in mind and i'll merge/release it.

[jonnii]

wat