gh-97 Bug fixes in dynamodb plugin

I have fixed a bug in insert() and delete() methods.There are also
some cosmetic changes to readme and properties files.

dynamodb/README

@@ -3,10 +3,13 @@ CONFIGURE
 YCSB_HOME - YCSB home directory
 DYNAMODB_HOME - Amazon DynamoDB package files
 
+Please refer to https://github.com/brianfrankcooper/YCSB/wiki/Using-the-Database-Libraries
+for more information on setup.
+
 BENCHMARK
 
-$YCSB_HOME/bin/ycsb load dynamodb -P worklaods/workloada -P dynamodb.properties
-$YCSB_HOME/bin/ycsb run dynamodb -P worklaods/workloada -P dynamodb.properties
+$YCSB_HOME/bin/ycsb load dynamodb -P workloads/workloada -P dynamodb.properties
+$YCSB_HOME/bin/ycsb run dynamodb -P workloads/workloada -P dynamodb.properties
 
 PROPERTIES
 

dynamodb/src/main/java/com/yahoo/ycsb/db/DynamoDBClient.java

@@ -249,7 +249,7 @@ public class DynamoDBClient extends DB {
             logger.error(ex.getMessage());
             return CLIENT_ERROR;
         }
-        return res.getConsumedCapacityUnits().intValue();
+        return OK;
     }
 
     @Override
@@ -267,7 +267,7 @@ public class DynamoDBClient extends DB {
             logger.error(ex.getMessage());
             return CLIENT_ERROR;
         }
-        return res.getConsumedCapacityUnits().intValue();
+        return OK;
     }
 
     private static Map<String, AttributeValue> createAttributes(