Update JCloudsStorageModule.java

getSizeInBlocks() returns the virtual blocks in the cloud side. There are 1048576 virtual blocks as stated in JCloudsStorageModule construtor, and there are 1048576/ BLOCK_IN_CLUSTER = mNumberOfCluster clusters.
So size in virtual blocks should be  mNumberOfCluster * BLOCK_IN_CLUSTER. It is coincidence that BLOCK_IN_CLUSTER and VIRTUAL_BLOCK_SIZE are equal. By the way, the cloud storage size is 1049576(virtual blocks) * 512(VIRTUAL_BLOCK_SIZE) = 536870912 bytes.~= 536M
ps:Cluster and blocks are confusing,as i am using s3 api.cluster is equal to object in s3.