Add notes support of meeting

The Meeting interface in package org.sakaiproject.coursemanagement.api has a notes property, while the Meeting interface in package org.sakaiproject.section.api.coursemanagement hasn't.

This make it impossible to show the notes value in 'Section Info' tool.

This patch aim to add 'notes' support to section-service (based on Sakai 2.9.2).
section-service.diff shows the changes of section-service
section-info.diff shows the changes of 'Section Info' tool.
Also the screen-shot is attached.