Added database connection

Code now connects to database and prints out errors. Also the ticket
table now includes a timestamp field

backend/src/models.rs

@@ -0,0 +1,30 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Debug, PartialEq, Deserialize)]
+pub enum category {
+    WhiteboardBeamer,
+    Internet,
+    IPadKoffer,
+    AppleTV,
+    DocuCam,
+    Sonstiges,
+}
+
+#[derive(Deserialize, Clone, PartialEq, Debug)]
+pub struct ticket {
+    pub id: i32,
+    pub category: category,
+    pub betreff: String,
+    pub description: String,
+    pub room: i16,
+    pub date: chrono::NaiveDateTime,
+    pub user_id: i16,
+}
+
+#[derive(Deserialize, Clone, PartialEq, Debug)]
+pub struct user {
+    pub id: i16,
+    pub first_name: String,
+    pub last_name: String,
+    pub is_admin: bool,
+}