Implemented P2P network protocol. Refactored project structure.

src/p2p/peer.rs

@@ -0,0 +1,20 @@
+use crate::p2p::State;
+
+pub struct Peer {
+    addr: String,
+    state: State,
+}
+
+impl Peer {
+    pub fn new(addr: String, state: State) -> Self {
+        Peer { addr, state }
+    }
+
+    pub fn get_state(&self) -> &State {
+        &self.state
+    }
+
+    pub fn set_state(&mut self, state: State) {
+        self.state = state;
+    }
+}