#187 Fix logging configuration for JAR product

[ndoschek]

• Update log configuration
  • If file path is given, reconfigure logging based on this configuration
  • Default case configures console logging to level INFO, no file logging
• Add ExampleServerLauncher.launch configuration that uses the example log configuration (console and file logging at level info)
• Remove log configuration files from classpath to avoid unwanted configuration aggregation
• Fix performance warning that causes log42j logging issue if executed in bundled jar
• Switch to import instead of require plugin bundles for log4j dependencies
• Update lib dependencies
  • Do not exclude source libs to improve debugging experiences in p2 use case
• Update README
  • Update logging section
  • Format via markdownlint and remove markdownlint warnings
  • Update import project section and remove outdated information
• targetplatform project
  • Include targetplatform as module of releng parent project to be able to import all projects as maven projects without exception
  • Remove unused targetplatform profile

Part of #187

Please also have a look at https://github.com/eclipse-emfcloud/emfcloud-modelserver-theia/pull/110

[ndoschek]

Thanks a lot for you review @cdamus, I addressed your comments with a separate commit, would be great if you could have another quick look, thanks again!