[TAP] Fix the TAP_SCHEMA mapping.
When defining in the configuration file a different name for TAP_SCHEMA content, the service implementor was also forced to define the same mapping in the database with the column `dbName`. This is no longer necessary. From now on, the `dbName` column will be ignored for all standard TAP_SCHEMA content. Instead, the name specified in the configuration file (if any) will be used instead. This way, the mapping for standard TAP_SCHEMA content is only specified once and at only one place: the configuration file. _This commit resolves the GitHub issue #98_