Add git commit hash and branch information to AboutActivity for debug builds

This will help us differentiate between custom/debug builds and release builds
of Aegis.

app/build.gradle

@@ -1,5 +1,17 @@
 apply plugin: 'com.android.application'
 
+def getCmdOutput = { cmd ->
+    def stdout = new ByteArrayOutputStream()
+    exec {
+        commandLine cmd
+        standardOutput = stdout
+    }
+    return stdout.toString().trim()
+}
+
+def getGitHash = { -> return getCmdOutput(["git", "rev-parse", "--short", "HEAD"]) }
+def getGitBranch = { -> return getCmdOutput(["git", "rev-parse", "--abbrev-ref", "HEAD"]) }
+
 android {
     compileSdkVersion 28
 
@@ -9,6 +21,8 @@ android {
         targetSdkVersion 28
         versionCode 21
         versionName "1.0.2"
+        buildConfigField "String", "GIT_HASH", "\"${getGitHash()}\""
+        buildConfigField "String", "GIT_BRANCH", "\"${getGitBranch()}\""
     }
 
     lintOptions {
@@ -80,5 +94,4 @@ dependencies {
     annotationProcessor 'com.github.bumptech.glide:compiler:4.9.0'
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.4.2'
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.4.2'
-
 }

app/src/main/java/com/beemdevelopment/aegis/ui/AboutActivity.java

@@ -1,15 +1,13 @@
 package com.beemdevelopment.aegis.ui;
 
 import android.content.Intent;
-import android.content.pm.PackageManager;
-import android.content.res.Resources;
-import android.graphics.Color;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 import android.view.View;
 import android.widget.TextView;
 
-import com.beemdevelopment.aegis.Preferences;
+import com.beemdevelopment.aegis.BuildConfig;
 import com.beemdevelopment.aegis.R;
 import com.beemdevelopment.aegis.Theme;
 import com.beemdevelopment.aegis.helpers.ThemeHelper;
@@ -22,7 +20,6 @@ import androidx.core.view.LayoutInflaterCompat;
 
 import de.psdev.licensesdialog.LicenseResolver;
 import de.psdev.licensesdialog.LicensesDialog;
-import de.psdev.licensesdialog.licenses.License;
 
 public class AboutActivity extends AegisActivity {
 
@@ -48,7 +45,7 @@ public class AboutActivity extends AegisActivity {
         btnLicenses.setOnClickListener(v -> showLicenseDialog());
 
         TextView appVersion = findViewById(R.id.app_version);
-        appVersion.setText(getCurrentVersion());
+        appVersion.setText(getCurrentAppVersion());
 
         View btnGithub = findViewById(R.id.btn_github);
         btnGithub.setOnClickListener(v -> openUrl(GITHUB));
@@ -74,13 +71,12 @@ public class AboutActivity extends AegisActivity {
         });
     }
 
-    private String getCurrentVersion() {
-        try {
-            return getPackageManager().getPackageInfo(getPackageName(), 0).versionName;
-        } catch (PackageManager.NameNotFoundException e) {
-            e.printStackTrace();
+    private static String getCurrentAppVersion() {
+        if (BuildConfig.DEBUG) {
+            return String.format("%s-%s (%s)", BuildConfig.VERSION_NAME, BuildConfig.GIT_HASH, BuildConfig.GIT_BRANCH);
         }
-        return "Unknown version";
+
+        return BuildConfig.VERSION_NAME;
     }
 
     private void openUrl(String url) {