feat: added optimisations from server_status

Closes #6

@juga, @gk: Me and @hiro were thinking of optimising server_status table as much as possible in the current effort of data-migration. I have made some updates, which primarily includes:

1. Removed of a few columns
2. Update datatypes of other columns (some strings to vectors)

I would request if each of us can review the table once, and add comments as to what each one of us feel can be improved in this table. Could be anything, datatypes, non-null columns, removal of extra columns, addition of new columns perhaps?