readwrite tool improvements
readwrite tool improvements

Now generates a list of filenames to use duing the setup, and passes this
list to the workers rather than having the workers list the bucket contents
or generate file names themselves.

Added a "warmup" stage that first writes out all the files so that content
exists for each filename.

Added setting the random seed as a command line parameter and uses this seed
for both generating the file names and the file content generator.

tobegit3hub/s3-tests,andrewgaul/s3-tests,Intel-bigdata/s3-tests,basho/s3-tests,tobegit3hub/s3-tests,SUSE/s3-tests,dreamhost/s3-tests,robbat2/s3-tests,SUSE/s3-tests,robbat2/s3-tests,piousbox/s3-tests,basho/s3-tests,Intel-bigdata/s3-tests,Nexenta/s3-tests,piousbox/s3-tests,timuralp/s3-tests,andrewgaul/s3-tests,ceph/s3-tests,Nexenta/s3-tests,smithfarm/s3-tests,jmunhoz/s3-tests,dreamhost/s3-tests,Nexenta/s3-tests,ceph/s3-tests,jmunhoz/s3-tests,piousbox/s3-tests,Nexenta/s3-tests,timuralp/s3-tests,smithfarm/s3-tests