1-step to update all files in a project

[papeh]

In a large project, it can be tedious to keep track of which localizable files have been added or deleted. It would be nice to have a one-step process to add, update, and delete files in Crowdin.
Basic design:

• Poll Crowdin for a list of existing files (https://support.crowdin.com/api/info/)
• Build a list of local files specified in crowdin.json
• Combine these two lists to create three lists: add (incl. new folders), update, delete
• Perform these three operations (perhaps we should delete only when the --prune option is specified)