Add support for specifying master's memory : critical when non trivial processing is done on it. Also add -server to the params
In yarn mode, run as the job user - not yarn user
Add support for changing write-timeout, and set default to 30s from the default 10s in yarn mode
When a block is dropped from memory to disk, it is not necessary that the disk size is same as memory size.
This change passes along the block's size in memory in the heartbeat - so that the masters view of the available free memory is same as the slaves.