OPENDJ-2006 Add Jul to Slf4j bridge

This commit adds support of the java.util.logging (Jul) to slf4j bridge.
Integration overview:
The jul-to-slf4j bridge has been added as a maven dependency. It simply
declares an Handler at the root level which redirect logs to slf4j.
Note that we still have to configure the Jul log level to avoid major
performance issue described here: http://www.slf4j.org/legacy.html#jul-
to-slf4.
Binding between Jul and slf4j log levels are described here:
http://www.slf4j.org/api/org/slf4j/bridge/SLF4JBridgeHandler.html
Binding between our loggers and Jul is done as follow:

* If there at least one Debug log publisher enabled then Jul level is
configured as FINEST.
* Else we compute the lowest level of all enabled error log publishers
and we apply the following binding between error log publisher default
severity and Jul Level:
    * DEBUG, INFORMATION, NOTICE -> Jul INFO
    * WARNING -> Jul WARNING
    * ERROR -> Jul SEVERE

Integration details:
The bridge is managed in the LoggerConfigManager.JulToSlf4jLogManager
inner class.
We compute the Jul log level when the following events occured:

* Add or remove a debug/error log publisher
* Error log publisher configuration change.