Allow developers to optionally sync a remote database and files

[gregharvey]

Suggested by @nfawbert, functionality for devs to be able to grab the latest nightly db backup of a project from live/prod and/or the uploaded files, if necessary, down to their local machine for use in ce-dev.

[gregharvey]

We were discussing this possibly being a ce-dev command rather than a ce-deploy driven thing (currently devs use mysql_sync) as that way we could try and catch a database connection early in the process and give a sane error message if we cannot connect.