feat(database): add integer type sizes

[DevPandi]

Extends #1972

SQLite: "INTEGER. The value is a signed integer, stored in 0, 1, 2, 3, 4, 6, or 8 bytes depending on the magnitude of the value."

PostgreSQL supports SMALLINT, INTEGER and BIGINT.

MySQL supporty TINY*, SMALL*, MEDIUM*, INTEGER and BITINT.

For simplicity's sake: SMALLINT, INTEGER, BIGINT. Less code, less complexity.

I also picked up on the ideas from the suggestion for text types.

[brendt]

For future reference: run composer qa locally before pushing, that way code style is properly fixed. I did it for you just now :)

[brendt]

Awesome!