As a developer, I can utilize a freelist to manage the data on disk so that the data is stored efficiently.

[30912hyl]

Trello: https://trello.com/c/d5STVgY9
Acceptance test: the database with freelist implementation has the same functionality as one without freelist
Given: A naive storage implementation (without freelist)
And: basic functionality tests for both implementations
When: tests are run, tests succeed
And: tests on the efficiency of disk usage
When: tests are run, the freelist implementation should be better than the naive implementation