factor out logic into lib/ and lib/builtins
store the builtins list in index.js
using minimist to parse args
fix the cd command
add pwd builtin, fix some tests
passing cd test
updated write test for PWD
factored out write test to use a different temp file each time, lots more failures
resolve files sent to write() from PWD, fixes tests
failing test for a relative read
fix for the read test to resolve paths
cross pwd off the list
1.2.0