Design standalone daemon structure

[geoah]

Requirements

The standalone daemon...

• should assume there is only one single user
• must be able to recursively scan a folder and match them with episodes
• must persist the user's shows, seasons, and episodes in theirlibrary
• must be able to go through the user's shows and find if there are missing (or new) episodes
• must be able to find download sources for the missing episodes
• must be able to download the missing episodes

  Changelog

• Adds standalone daemon cmd outline
• Adds structs for Show, Season, Episode
• Adds interface for Differ and concrete outline for SimpleDiff
• Adds interface for Downloader and concrete outline for TorrentDownloader
• Adds interface for Finder and concrete outline for FinderTorrent
• Adds interface for Library and concrete outline for TraktLibrary and UserLibrary
• Adds interface for Watcher and concrete outline for FileWatcher

  To do

• Refactor interface and concrete implementations naming
• Add an HTTP interface to manage user library in standalone daemon
• Add a way to find newly released episodes and download them
• Add an RSS exporter instead of downloading episodes directly

Edit: On second thought, the last three to-do items are not really required for a proof of concept so we can skip them for now.

[superdecimal]

Should we add a db interface too?

[geoah]

@superdecimal I made it part of #4 as it is the only thing that will need it for now

This also requires the creation of an interface, and a concrete implementation of a persistence datastore. The first concrete implementation could be any NoSQL database; preferably rethinkdb but any will do.