tauri@0.6.0

Adds a command line interface option to tauri apps, configurable under tauri.conf.json > tauri > cli.
Fixes no-server mode not running on another machine due to fs::read_to_string usage instead of the include_str macro. Build no longer fails when compiling without environment variables, now the app will show an error.
Adds desktop notifications API.
Properly reflect tauri.conf.json changes on app when running tauri dev.