build for both GM104 and GM204

For the GTX 750 and new 970/980

also fix -a luffa parameter for 1.4.4 release
use cudart_static.lib, keep SM 5.0 by default

SM 5.2 works also on the 750 Ti but if we specify both at compile time,
hash speed will be reduced (the 750Ti will use 5.2 which is not optimal)
Try some obscure cuda flags (kbomba)

http://devblogs.nvidia.com/parallelforall/separate-compilation-linking-cuda-device-code/
enhance solo mining, update http headers

and prepare next version...