Implement OpenSslEngine.getSupportedCipherSuites() and get/setEnabledCipherSuites()

Motivation:

To make OpenSslEngine a full drop-in replacement, we need to implement
getSupportedCipherSuites() and get/setEnabledCipherSuites().

Modifications:

- Retrieve the list of the available cipher suites when initializing
  OpenSsl.
- Improve CipherSuiteConverter to understand SRP
- Add more test data to CipherSuiteConverterTest
- Add bulk-conversion method to CipherSuiteConverter

Result:

OpenSslEngine should now be a drop-in replacement for JDK SSLEngineImpl
for most cases.
Raise an exception when the specified cipher suite is not available

Motivation:

SSL_set_cipher_list() in OpenSSL does not fail as long as at least one
cipher suite is available.  It is different from the semantics of
SSLEngine.setEnabledCipherSuites(), which raises an exception when the
list contains an unavailable cipher suite.

Modifications:

- Add OpenSsl.isCipherSuiteAvailable(String) which checks the
  availability of a cipher suite
- Raise an IllegalArgumentException when the specified cipher suite is
  not available

Result:

Fixed compatibility