added HMAC-SHA library, jsSHA

Will have to add tests and example usage in Wiki.
Waiting on permission okay from author...
sha.js lib tests
sha.js lib tests
Merge pull request #152 from bFraley/shajs

hmac-sha support (shaJS library)
- Minor array optimizations
Merge branch 'master' of github.com:maximecb/Higgs
- Runtime optimizations for 3d-cube benchmark