Prevent R CMD check from using /tmp

When R CMD check is run on the SparkR package it leaves behind files in /tmp which is a violation of CRAN policy. We should instead write to Rtmpdir. Notes from CRAN are below

Checking this leaves behind dirs

   hive/$USER
   $USER

and files named like

   b4f6459b-0624-4100-8358-7aa7afbda757_resources

in /tmp, in violation of the CRAN Policy.