First pass at CONTRIBUTING.md
Merge pull request #30 from adamcaudill/contrib_guide

CONTRIBUTING.md
renaming file to match class name
Adding crypto_generichash_blake2b_salt_personal #7

Make sure libsodium version is > 0.4.5
salt personal and key
rolling back to generating random key
fixing the parameters
defining blake constants
fix GenericHashSaltPersonal method signature
fixing test method name