camera-traps high level design

[richcar58]

Define the externally visible Rust interfaces, mainly the camera-traps application's events and public methods/functions. Also included in this design is the Rust module layout and concurrency control.

• [x] Define, read and parse toml configuration file
• [x] Implement all events and their interfaces
• [x] Initialize event engine
• [x] Initialize each internal plugin
• [x] Test event processing with internal plugins