we're always checking the configuration encrypted.
saying it is 'preferred' encrypted is misleading,
therfore, just remove it.
i do not think, it is worth saying that we do not query 'http',
this is clear from the source code.
moreover, fix two typos.
This certificate does not exist on older Android phones.
It is already added manually for IMAP and SMTP,
this commit adds the same certificate for HTTP requests.
async-smtp does not implement read buffering anymore
and expects library user to implement it.
To implement read buffer, we wrap streams into BufStream
instead of BufWriter.
