Support Windows 7 64bit VS2012 and fixed CUDA grid blocks limited.

1. Fixed bug of CUDA max grid of blocks limited. #12 #282 #707
2. Support Windows 7 64bit VS2012. #652  #643 #15 
3. Add USE_LMDB for LMDB in Makefile. 
We should not use the flag of `O_BINARY` here. Because it reads from text file not binary file.