sql: ddl: initial version

This commit marks the first version of the database backend.

It was generated for a Oracle DB, next commit will convert
it for mysql.

Tables;
 * Comments
 * Messages
 * Rules
 * Topic
 * User_Rules (intersec.)
 * User

Signed-off-by: Alexander Christ <alex.christ@hotmail.de>
sql: convert oracle to mysql

Convert it to mysql, should be installable.

For now only tables work, foreign keys are not added yet.
Also there is an issue with the timestamp, can cause
problems in the future.

Signed-off-by: Alexander Christ <alex.christ@hotmail.de>