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 certificates were missing the digitalSignature and keyAgreement
usage types, of which at least digitalSignature was checked by CyaSSL.
This caused the test server in test 310 (among others) to fail the
startup verification and therefore run (see
http://curl.haxx.se/mail/lib-2014-07/0303.html).