configuration for cg1.4xlarge instance type and new version of cuda miner

- using ansible best practices, split cg1.4xlarge & c2.2xlarge into
separate groups. majority of configuration now in group_vars dir
- move cudaminer to new version which has significantly increased
hashing from ~150khash to ~250 khash while also reducing CPU component.
thread allocation for cpuminer has also been increased for both
instance types.