OPENDJ-879 (CR-1603) Add HTTP access log


Consolidated common code for the *Logger classes prior to implementing the HTTP access log.


AbstractLogger.java: ADDED
Pulled up from the *Logger classes.

AccessLogger.java, ErrorLogger.java, DebugLogger.java:
Now inherit from AbstractLogger.
Removed code pulled up into AbstractLogger: initializeErrorLogger(), isConfigurationAddAcceptable(), applyConfigurationAdd(), applyConfigurationChange(), isConfigurationDeleteAcceptable(), applyConfigurationDelete(), isJavaClassAcceptable(), getErrorPublisher().
Added the loggerStorage static variable.
Added a ctor + implemented getJavaClassPropertyDefinition() and getStorage().

LoggerConfigManager.java:
Replaced the calls to the various initialize*Logger() methods with calling initializeLogger().
Extracted method getLoggerInstance() and used it in all the other methods.


LogPublisherConfiguration.xml:
Pulled up the declaration of "java-class" property here from sub configurations.

AccessLogPublisherConfiguration.xml, DebugLogPublisherConfiguration.xml, ErrorLogPublisherConfiguration.xml, LogPublisherConfiguration.xml:
Replaced the declaration of "java-class" property by a property-override.

StaticUtils.java:
Added close(Collection<Closeable>)