Add Wordpress importer plugin

[edtjones]

We should have the WordPress importer plugin installed so people can migrate to rooftop easily. This needs some thought to make sure we aren't going to bog down the servers with long-running synchronous requests

[edtjones]

The delay with this is the fact that the importer runs in the same thread as the application; giving every user the ability to import stuff feels like a performance risk so we're looking at options to offload.