Create a new enum WeightUnit ; #187 - subtask.

src/main/java/de/dennisguse/opentracks/settings/WeightUnit.java

@@ -0,0 +1,23 @@
+package de.dennisguse.opentracks.settings;
+
+import de.dennisguse.opentracks.R;
+
+public enum WeightUnit {
+    POUND(R.string.unit_pound),
+    KILOGRAM(R.string.unit_kilogram);
+
+    private final int preferenceIdentifier;
+
+    WeightUnit(int preferenceIdentifier) {
+        this.preferenceIdentifier = preferenceIdentifier;
+    }
+
+    public int getPreferenceId() {
+        return preferenceIdentifier;
+    }
+
+    // If you need a default value, you can define it here
+    public static WeightUnit defaultWeightUnit() {
+        return KILOGRAM;
+    }
+}