Standalone distribution - Slf4j Logging

[bmontuelle]

Pull Request Description

We are using oxalis-ng in standalone mode and would like to have the exceptions and informational messages logged with Slf4j underlying infrastructure so we can collect them like the rest of the oxalis platform.

Type of Pull Request

• New feature/Enhancement - non-breaking change which adds functionality
• Bug fix
• Breaking change (Require Major version change?)

Type of Change

• OpenPeppol eDEC Specifications
• Peppol AS4 Profile specification
• Peppol Business Envelope specification
• Peppol Policies specification
• Peppol eDEC Code Lists specification
• OpenPeppol Spring/Fall release
• Oxalis software internal change or enhancement
• General change

Pull Request Checklist:

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas. But did not add unnecessary annotation/comment say @author name etc
• I have checked my code for variable and method name and corrected grammar/spelling mistakes if any
• I have made corresponding changes to the documentation where needed
• My changes generate no new/additional warnings
• My change is not breaking or creating conflict with associated dependencies
• I have performed a self-review of my own code
• I ran mvn clean install before commit and all tests run successfully
• I conducted basic QA to assure all features are working fine
• My pull request generate no conflicts with master branch
• I requested code review from other team members