Added feh handler

src/handlers/feh.rs

@@ -1,5 +1,15 @@
 use crate::Wallpapers;
 
+use std::process::Command;
+
 pub fn change_wallpapers(wallpapers: &Wallpapers) {
-    println!("Not implemented");
+    let mut command = Command::new("/usr/bin/feh");
+    command.arg("--no-fehbg").arg("--bg-fill");
+
+    for monitor in wallpapers.config.monitors.monitors.iter() {
+        command.arg(wallpapers.random_selection(monitor).to_string());
+    }
+
+    let _result = command.output();
+    println!("{:?}", command.get_args());
 }