Merge pull request #44 from herlo/patch-2

remove owner.group from chmod command

Initial release, ready for production use. Features include:

    - 128-bit random nonce used for the URL
    - 3 dynamically generated static salts for building file, AES, and HMAC
      keys
    - Keys dynimacially built with PBKDF2
    - All notes AES-256 CTR encrypted
    - All notes protected and authenticated with HMAC-SHA512
    - Hashcash tokens minted by the client and submited to the server
    - Anonymous browser fingerprints used for the Hashcash resource string
    - QR code created for sharing the encrypted note via mobile devices
    - POST data hidden to discourage server-side logging of the URL