Add SD card permission for pre-Kitkat devices. This was causing an issue for some imports

Update version number for v2.3.0-beta2 update

Author: codinguser

app/build.gradle

@@ -6,7 +6,7 @@ apply plugin: 'io.fabric'
 def versionMajor = 2
 def versionMinor = 3
 def versionPatch = 0
-def versionBuild = 1
+def versionBuild = 2
 
 static def buildTime() {
     def df = new SimpleDateFormat("yyyyMMdd HH:mm 'UTC'")

app/src/main/AndroidManifest.xml

@@ -45,6 +45,9 @@
     <uses-permission android:name="android.permission.INTERNET"
                      android:label="Export and backup to 3rd party hosting services" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
+        android:label="Import books and backup files into GnuCash"
+        android:maxSdkVersion="18" />
 
     <application android:name="org.gnucash.android.app.GnuCashApplication"
         android:icon="@drawable/ic_launcher"