Initial commit

Trawls /usr/share/dict/words for random words (four by default, number
may be specified as first argument on command line).
Add commentary
Build dictionary sans proper nouns
Build separate dictionaries based on word length
Build passphrases within a range of sizes

Uses dictionary files containing words of specific lengths, built by the
divide_dictionary.py script.
Merge branch 'master' of https://github.com/lonnon/passphrase
Fill in the README