Allow User to Set File Encoding

[tsmanner]

All encryption/decryption and file read/write is assuming a file encoding of UTF-8. We should add a setting and update the encryption api to consume it.

[tsmanner]

@manistal Does this actually matter? I'm playing with the file writing and Base64 stuff, it requires bytes objects not str objects. bytes have to be encoded, but I guess the Base64Engine can just decide it encodes as utf-8, and any other thing will be operating on the raw bytes and yielding a string anyway?