List defaults for all the boolean options

[callumlocke]

It would be good to clarify the defaults for these in the readme:

    forceDelete: bool, // Whether to overwrite existing directory or not
    excludeHiddenUnix: bool, // Whether to copy hidden Unix files or not (preceding .)
    preserveFiles: bool, // If we're overwriting something and the file already exists, keep the existing
    preserveTimestamps: bool, // Preserve the mtime and atime when copying files
    inflateSymlinks: bool, // Whether to follow symlinks or not when copying files
    whitelist: bool, // if true every file or directory which doesn't match filter will be ignored