cleanup actionbar style definition

src/main/res/drawable/main_header_bg.xml

@@ -1,27 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-  ownCloud Android client application
-
-  Copyright (C) 2012  Bartek Przybylski
-  Copyright (C) 2015 ownCloud Inc.
-
-  This program is free software: you can redistribute it and/or modify
-  it under the terms of the GNU General Public License version 2,
-  as published by the Free Software Foundation.
-
-  This program is distributed in the hope that it will be useful,
-  but WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-  GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License
-  along with this program.  If not, see <http://www.gnu.org/licenses/>.
--->
-<shape xmlns:android="http://schemas.android.com/apk/res/android">
-    <gradient
-        android:startColor="@color/primary"
-        android:endColor="@color/primary"
-        android:angle="270"
-     />
-    <corners android:radius="0dp" />
-</shape>

src/main/res/values/styles.xml

@@ -150,8 +150,8 @@
 	
 	<style name="Theme.ownCloud.Widget.ActionBar"
 		parent="style/Widget.AppCompat.Light.ActionBar.Solid.Inverse">
-		<item name="android:background">@drawable/main_header_bg</item>
-		<item name="background">@drawable/main_header_bg</item>
+		<item name="android:background">@color/primary</item>
+		<item name="background">@color/primary</item>
     	<item name="android:textColor">#ffffff</item>
     	<item name="android:shadowColor">#222222</item>
     	<item name="android:shadowRadius">1</item>