android: Explicitly apply default theme to dialogs

When you don't specify a theme the platform defaults back to gingerbread
styling. By applying the device default theme it will change it to the
new (and much nicer looking) styles on newer devices.

close #18
diff --git a/src/android/Notification.java b/src/android/Notification.java
index 23312b4..456a9bf 100755
--- a/src/android/Notification.java
+++ b/src/android/Notification.java
@@ -151,7 +151,7 @@
         Runnable runnable = new Runnable() {
             public void run() {
 
-                AlertDialog.Builder dlg = new AlertDialog.Builder(cordova.getActivity());
+                AlertDialog.Builder dlg = new AlertDialog.Builder(cordova.getActivity(), AlertDialog.THEME_DEVICE_DEFAULT_LIGHT);
                 dlg.setMessage(message);
                 dlg.setTitle(title);
                 dlg.setCancelable(true);
@@ -192,7 +192,7 @@
 
         Runnable runnable = new Runnable() {
             public void run() {
-                AlertDialog.Builder dlg = new AlertDialog.Builder(cordova.getActivity());
+                AlertDialog.Builder dlg = new AlertDialog.Builder(cordova.getActivity(), AlertDialog.THEME_DEVICE_DEFAULT_LIGHT);
                 dlg.setMessage(message);
                 dlg.setTitle(title);
                 dlg.setCancelable(true);
@@ -270,7 +270,7 @@
             public void run() {
                 final EditText promptInput =  new EditText(cordova.getActivity());
                 promptInput.setHint(defaultText);
-                AlertDialog.Builder dlg = new AlertDialog.Builder(cordova.getActivity());
+                AlertDialog.Builder dlg = new AlertDialog.Builder(cordova.getActivity(), AlertDialog.THEME_DEVICE_DEFAULT_LIGHT);
                 dlg.setMessage(message);
                 dlg.setTitle(title);
                 dlg.setCancelable(true);
@@ -398,7 +398,7 @@
         final CordovaInterface cordova = this.cordova;
         Runnable runnable = new Runnable() {
             public void run() {
-                notification.progressDialog = new ProgressDialog(cordova.getActivity());
+                notification.progressDialog = new ProgressDialog(cordova.getActivity(), AlertDialog.THEME_DEVICE_DEFAULT_LIGHT);
                 notification.progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                 notification.progressDialog.setTitle(title);
                 notification.progressDialog.setMessage(message);