Added: aes example

Simple aes shell to encrypt arbitrary strings and decrypt aes blocks.
You can use 'encrypt <key> <msg>' and 'decrypt <key> <block>':

  AES Shell
  > encrypt foo bar
  encrypt foo bar
  Block 0:	71 5c 59 fd 78 1c 12 a4 c2 52 be e1 d1 17 a0 db
  > decrypt foo "71 5c 59 fd 78 1c 12 a4 c2 52 be e1 d1 17 a0 db"
  decrypt foo "71 5c 59 fd 78 1c 12 a4 c2 52 be e1 d1 17 a0 db"
  bar