Add callbacks support

[dmathieu]

Hello,

It'd be super cool if we'd be able to add some callbacks to the deployment.
For exemple, I'm using the GitHub Javascript Strategy to bundle my JS and CSS. And I'd really like to do it automatically every time I deploy.

[jqr]

What callbacks would you like to see? pre_deploy and maybe a post_deploy?

[dmathieu]

Yes I think that would be enough.

[jqr]

Just released 0.2.2 which has these callbacks:
rake after_deploy # Callback after deploys
rake before_deploy # Callback before deploys

You can define as many rake tasks as you like to be run as before or after deploy tasks.

[iamnader]

To use an after_deploy callback should we define the task in our own heroku.rake file like this:
task :my_task => :after_deploy do
...
end

[iamnader]

Ah, I see that you can just define another :after_deploy task. Thanks.

[dmathieu]

Yes. Tasks are just tasks. As long as they are included soon enough, they can be defined in any file you want.

[jqr]

Happily accepting documentation patches :)