Add settings wrapper

app/src/main/java/com/github/gotify/Settings.java

@@ -0,0 +1,61 @@
+package com.github.gotify;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+
+import com.github.gotify.client.model.User;
+
+public class Settings {
+    private final SharedPreferences sharedPreferences;
+
+    public Settings(Context context) {
+        sharedPreferences = context.getSharedPreferences("gotify", Context.MODE_PRIVATE);
+    }
+
+    public void url(String url) {
+        sharedPreferences.edit().putString("url", url).apply();
+    }
+
+    public String url() {
+        return sharedPreferences.getString("url", null);
+    }
+
+    public boolean tokenExists() {
+        return token() != null;
+    }
+
+    public String token() {
+        return sharedPreferences.getString("token", null);
+    }
+
+    public void token(String token) {
+        sharedPreferences.edit().putString("token", token).apply();
+    }
+
+    public void clear() {
+        url(null);
+        token(null);
+    }
+
+    public void user(String name, boolean admin) {
+        sharedPreferences.edit().putString("username", name).putBoolean("admin", admin).apply();
+    }
+
+    public User user() {
+        String username = sharedPreferences.getString("username", null);
+        boolean admin = sharedPreferences.getBoolean("admin", false);
+        if (username != null) {
+            return new User().name(username).admin(admin);
+        } else {
+            return new User().name("UNKNOWN").admin(false);
+        }
+    }
+
+    public String serverVersion() {
+        return sharedPreferences.getString("version", "UNKNOWN");
+    }
+
+    public void serverVersion(String version) {
+        sharedPreferences.edit().putString("version", version).apply();
+    }
+}