Merge pull request #960 from kelektiv/release-v5-1-0

Update `node-pre-gyp` to 1.0.0

v5.0.0

 - Fix the bcrypt "wrap-around" bug. It affects passwords with lengths >= 255.
   It is uncommon but it's a bug nevertheless. Previous attempts to fix the bug
   was unsuccessful.
 - Experimental support for z/OS
 - Fix a bug related to NUL in password input
 - Update `node-pre-gyp` to 0.15.0