build status and coverage "badges" in README
node_modules/ and coverage/ in gitignore
move buster and coveralls to devDependencies
end-to-end steganography

Including a "plain" codec that just encodes
8-bit character codes for each character.
Should be replaced by something smarter
later.
Crypto -> AESCrypto

To emphasize that the crypto layer, much like
the character encoding layer, should be kept
modular and that AES is only one out of many
possibilities.

(However, this layer is currently slightly
leakier than the encoding layer -- e.g. the
Ordering functions reach into AESCrypto to
make use of the strong randomness functions
from CryptoJS. This could be resolved by
making them use CryptoJS directly, or by
creating a general Crypto module for
mechanism-independent crypto functionality.)