Fixing useSslClientAuthentication option:

- according documentation and internet examples to enable SSL client authentication on com.sun.net.httpserver.HttpsServer it is necessary to set params.setNeedClientAuth(useClientAuthentication) but also defaultSSLParameters.setNeedClientAuth(useClientAuthentication) in org.jolokia.jvmagent.JolokiaServer.JolokiaHttpsConfigurator#configure
- Boolean.getBoolean(auth) --> Returns true if and only if the system property named by the argument exists and is equal to the string "true".
  Boolean.valueOf(auth)    --> Returns a Boolean with a value represented by the specified string.