Don't pretend that current Base64 "assertion" works, it doesn't

[doesdev]

The regex based Base64 check is deeply flawed and caused me to encounter stupid bugs. Probably would if others used this as well. Bottom line is either an encoding assertion is guaranteed or it should not be asserted. Practically speaking that means I probably need to attempt decoding it as base64 and catch an error. Either that or remove the base64 check altogether and follow the chain down.