Allow components to participate to logging configuration

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Move nexus loggers configuration to CoreLogConfigurationCustomizer from logback-nexus.xml

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Make possible to unset a logger

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Move configuration logic to logback manager (from logging plugin)

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Add DEFAULT logging level that will reset level to its effective level

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Add UTs for read/write of logback-overrides.xml

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Replace LoggerContributor with LogConfigurationCustomizer in atlas plugin

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Replace LoggerContributor with LogConfigurationCustomizer in wonderland plugin

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Drop LoggerContributor and move configuration logic to log manager

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>