Replace scrypt library
Update RESOURCES.md
Update CONTRIBUTING.md
README: Make wording less confusing

Append implies something existing and "analyzing cipertext" implies "not the header".
Merge pull request #51 from ecki/patch-1

README: Make wording less confusing
Email as salt!

See discussion at #45
Merge branch 'master' into salt

* master:
  README: Make wording less confusing
  Update CONTRIBUTING.md
  Update RESOURCES.md
  Replace scrypt library
  Move salt pull request to its own branch
Focus email field first
Fix #50
Remove duplicate text, instead explain email usage