about: add missing elements

This commit adds two missing elements on the about screen:
- a short description of Ring
- the authors and artists list

Change-Id: Id141bfa77378449b08d165a7b32688fe34f45f19
Reviewed-by: Hadrien De Sousa <hadrien.desousa@savoirfairelinux.com>
Tuleap: #1574
diff --git a/ring-android/app/src/main/res/layout/dialog_about.xml b/ring-android/app/src/main/res/layout/dialog_about.xml
new file mode 100644
index 0000000..7ac4ac4
--- /dev/null
+++ b/ring-android/app/src/main/res/layout/dialog_about.xml
@@ -0,0 +1,57 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:padding="@dimen/padding_medium">
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginLeft="5dp"
+            android:layout_marginRight="5dp"
+            android:layout_marginTop="5dp"
+            android:text="@string/developed_by"
+            android:textColor="@color/color_primary_dark"
+            android:textSize="18sp" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginBottom="5dp"
+            android:layout_marginLeft="5dp"
+            android:layout_marginRight="5dp"
+            android:text="@string/credits_developer"
+            android:textAppearance="?android:attr/textAppearanceSmall" />
+
+        <View
+            android:layout_width="match_parent"
+            android:layout_height="1dp"
+            android:background="@color/darker_gray" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginLeft="5dp"
+            android:layout_marginRight="5dp"
+            android:layout_marginTop="5dp"
+            android:text="@string/designed_by"
+            android:textColor="@color/color_primary_dark"
+            android:textSize="18sp" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginBottom="5dp"
+            android:layout_marginLeft="5dp"
+            android:layout_marginRight="5dp"
+            android:text="@string/credits_designer"
+            android:textAppearance="?android:attr/textAppearanceSmall" />
+
+    </LinearLayout>
+
+</ScrollView>
\ No newline at end of file