email: add support for Server Name Indication (SNI)

Change the underlaying socket factory reference to SSLCertificateSocketFactory which
has support for SNI since 4.2, and remove the access to the obsolete methods from
the old factory reference.
This change will setup the socket with a proper hostname prior to the ssl handshake.

Change-Id: Ie537b1d8c3da33de3665e481320be134939155ca
Signed-off-by: Jorge Ruesga <j.ruesga.criado@gmail.com>
Merge "email: add support for Server Name Indication (SNI)"