feat(Logger): Implement LogAPI

[Hipska]

Base information

Question	Answer
Related to a SourceForge thead / Another PR / Combodo ticket?	N/A
Type of change?	Enhancement

Objective

Currently this module logs in a separate file and doesn't use the same format as the regular error.log. Which makes it harder/impossible to investigate using the Logs Center from itop-log-mgmt included in iTop Products.

Proposed solution

Refactor the existing Logger to implement the LogAPI by extending IssueLog, which makes it use the same structure in the file and also use the same error.log. Channel is set to SAML so these logs can easily be filtered out for investigation. Also the same behaviour regarding the debug module setting is kept. Default log level is Warning, but set to Trace when debug is set to true.

Checklist before requesting a review

• I have performed a self-review of my code
• I have tested all changes I made on an iTop instance
• Would a unit test be relevant and have I added it?
• Is the PR clear and detailed enough so anyone can understand without digging in the code?

Checklist of things to do before PR is ready to merge

• Maybe change the level of some existing log messages to be more consistent with the rest of the product?