fix a little typo in public_key documentation

In the example of `public_key:pem_entry_encode/2`, the result
should match to `PemEntry` rather than to `PemBin` since `PemEntry`
is expected as an input argument of `public_key:pem_encode/1` called
just on the next line of the example.
public_key: change encoding to utf8
public_key: Workaround for incorrectly encoded utf8 emailAddress

Author: Daniel Barney <daniel@pagodabox.com>
Date:   Thu Oct 25 14:33:11 2012 -0600

    Most common browsers are lax in thier handling of how the
    emailAddress field is encoded. RFC 3280 section 4.1.2.6
    defines the encoding as IA5String, however browsers will
    also handle certificates with the emailAddress field
    encoded as UTF8String. This fix allows the emailAddress
    to be decoded as both an IA5String and an UTF8String.

Reviewed by: Andrew Bennett <andrew@pagodabox.com>
public_key_SUITE: Rename id-at-countryName to id-emailAddress
ssl, public_key: Dialyzer fixes
Prepare release