Bump bcrypt to 0.7.8 t solve build issues on Win64

bcrypt 0.7.7 fails to build on Win64 via node-gyp claiming unable to find "openssl/rand.h" though all dependencies are available whereas 0.7.8 builds fine.
Merge pull request #3 from bentolor/patch-1

Bump bcrypt to 0.7.8 t solve build issues on Win64