[x] add auto user serialization by the use of ORM into db
[x] Also allow the easy switch of sql db (from MySQL to postgres in v4.1.0). Note that postgres is preferred because we deal a lot with JSONs, and it is the only one Sequelize that supports JSON. One can switch back to MySQL easily of course, since it's only a change of dialect of the ORM.
[x] work for CGKB will begin, after confirmation that ORM cannot efficiently support it. Will use an additional graph db for the brain, along with sql.
v4.1.0: