JAVA-444: make ensureIndex first do a read on index collection to see if index exists

* If an embedded field was referenced in an index a hard failure
  occurred,  due to triggering of the 'no dots in key names' logic
  via the insert.  Moved code to use the lower level API method which
  permits disabling of key checks.

Author: Brendan W. McAdams

src/main/com/mongodb/DBApiLayer.java

@@ -359,10 +359,10 @@ public void createIndex( final DBObject keys, final DBObject options, DBEncoder
                 full.put( k , options.get( k ) );
             full.put( "key" , keys );
 
-            DBCollection idxs = DBApiLayer.this.doGetCollection( "system.indexes" );
+            MyCollection idxs = DBApiLayer.this.doGetCollection( "system.indexes" );
             //query first, maybe we should do an update w/upsert? -- need to test performance and lock behavior
             if ( idxs.findOne( full ) == null )
-                idxs.insert( new DBObject[] { full }, WriteConcern.SAFE, encoder );
+                idxs.insert( new DBObject[] { full },  false, WriteConcern.SAFE, encoder );
         }
 
         final String _fullNameSpace;