Synch DB helper creation with use of other instances.

clients/android/NewsBlur/src/com/newsblur/database/BlurDatabaseHelper.java

@@ -56,9 +56,11 @@ public class BlurDatabaseHelper {
     public BlurDatabaseHelper(Context context) {
         this.context = context;
         dbWrapper = new BlurDatabase(context);
+        synchronized (RW_MUTEX) {
             dbRO = dbWrapper.getRO();
             dbRW = dbWrapper.getRW();
         }
+    }
 
     public void close() {
         // when asked to close, do so via an AsyncTask. This is so that (since becoming serial in android 4.0)