Added failure scripts/data

- readme defines some failure policies, e.g. 'F0'
- funcs updated to allow pausing/resuming of Cassandra daemon
- driver script added 'cstop' 'cresume' which calls into funcs to halt Cassandra
instance on localhost (need to be superuser)
- execute fail-F0.sh as root on some non-seed node at same time as YCSB run to
affect YCSB with F0 failure pattern

bzip file added is entire log of YCSB instance. Interestingly, [RW]-TS entries
seemed to pause when is50 was paused, despite YSCB being told it can connect to
other Cassandra nodes (32 threads).