vmem: implementation of vmem_check

Validate pool consistency.
-Check wrong data in header
-Check not zeroed values inside a zeroed pages
-Check data structures are outside of memory region
-Check conflict memory regions between pools
Merge pull request #34 from spawlows/vmem-pool-check-merged

vmem: implementation of vmem_check
common: NVML renaming and library splitting

Rename functions in library and split libpmem.
-Rename typdefs: PMEMblkpool, PMEMlogpool, PMEMobjpool
-Split libpmem into libpmem, libpmemblk, libpmemlog, libpmemobj
-Rename trn => obj and add pmemobj fake implementation
-Add benchmark building to make check target
-Change functions _map() to _pool_open()
-Update scope tests