Hide secret URL from post

Taken from https://github.com/burntout/d-note/commit/e09e4a8147097a99cd273945abdb035e67120f84
Change 16-byte filename, AES-256 and HMAC-SHA512

This is a massive change to maximize security and bring the URL back to 22
base64 characters. This push would not be possible without Alan Dawson -
https://github.com/burntout/.
fix some install steps
Move ZLIB compression and decompression

Compression should be the last thing done before encoding for encryption and the
first thing done after decoding for decryption.
Move compression back

Compression must happen before the encryption for 2 reasons:

    1- Compression is inefficient on encrypted data
    2- Encryption is meant to hide patterns. Compressing after encryption
    reveals some

Bad regression. I should not be allowed to code immediately after waking up. :)
remove dependency on python-pbkdf2. use python-crypto instead
import stylistic change
Remove unnecessary import statement. Cleanup note.
add missing quotes for consistency