The previous test certificates contained RSA keys of only 1024 bits.
However, RSA claims that 1024-bit RSA keys are likely to become
crackable some time before 2010. The NIST recommends at least 2048-bit
keys for RSA for now.
Better use full 2048 also for testing.
Closes#2973
The previous test certificate contained a MD5 hash which is not
supported using TLSv1.2 with Schannel on Windows 7 or newer.
See the update to this blog post on IEInternals / MSDN:
http://blogs.msdn.com/b/ieinternals/archive/2011/03/25/
misbehaving-https-servers-impair-tls-1.1-and-tls-1.2.aspx
"Update: If the server negotiates a TLS1.2 connection with a
Windows 7 or 8 schannel.dll-using client application, and it
provides a certificate chain which uses the (weak) MD5 hash
algorithm, the client will abort the connection (TCP/IP FIN)
upon receipt of the certificate."
