Add a setting to append additional code to wsgi/fcgi deployment scripts

[dbreen]

The existing initialization setting is handy for adding extra code to the wsgi files such as for loading celery, but for other purposes like New Relic integration, there's no way to wrap the application object with an agent. This change creates a new deploy_script_extra setting that appends its value to the .wsgi/.fcgi files.

Example usage:

deploy_script_extra =
    import newrelic.agent
    newrelic.agent.initialize('/etc/newrelic.ini', 'app')
    application = newrelic.agent.WSGIApplicationWrapper(application)

[reinout]

I copied the code to the latest master and merged it. Looks useful!

I'll make a release soon.

[reinout]

Warning: in 1.10 I renamed the deploy_script_extra option to deploy-script-extra for consistency with the other options. So: dashes instead of underscores.

I do raise an error when the old one is found, as it seems pretty essential for your deployments and the error shouldn't pass through silently.

[dbreen]

Makes sense, thanks for the heads up!