New error logs with more details. Update of the doc with english version

README.md

README_FR-fr.md

pom.xml

src/main/java/fr/soleil/opcuaproxy/AOpcUaSubscriber.java

...roxy/connector/OpcUaClientSecurityCertificateFactory.java

.../opcuaproxy/connector/OpcUaClientSecurityNoneFactory.java

...java/fr/soleil/opcuaproxy/connector/OpcUaProxyClient.java