Merge Rule Metadata into Rule

For SONAR-8867 (SonarQube 6.4), we have separated rule metadata from rule definition and each has its own table, as some fields were specific to an organization. Organizations have been dropped from SonarQube with SONAR-14245 in SQ 8.7.

Now we don't need this separation anymore, rule metadata should be just a part of rule definition; not only will this simplify the db query but also we will have less class and object to manage.