App architecture modifications.

Now GUI and the app itself is divided into two different binaries.
The app also provides system tray icon.
Whereas the GUI can be used to configure the app.

app/src/log.rs

@@ -0,0 +1,21 @@
+use simple_log::LogConfigBuilder;
+
+use crate::config;
+use crate::APP_LOG_DIR;
+
+pub fn init_logging() -> Result<(), String> {
+    // configure logging
+    let config = LogConfigBuilder::builder()
+        .path(format!("{}/{}", APP_LOG_DIR.get().unwrap().display(), config::LOG_FILE_NAME))
+        .size(1 * 100)
+        .roll_count(10)
+        .time_format("%Y-%m-%d %H:%M:%S.%f") //E.g:%H:%M:%S.%f
+        .level("debug")
+        .output_file()
+        .output_console()
+        .build();
+
+    simple_log::new(config)?;
+
+    Ok(())
+}