Use `sqlite-diffable` as a Python module

[PeskyPotato]

The pull list of changes are described in Issue #9, the summary can be found below:

• Created wrapper functions for load, dump and object using click and sample code from this StackOverflow post.

• Added tests for dumping one and two tables, and loading two tables.

[PeskyPotato]

If all looks good, I wouldn't mind also updating the README to show some example usage instructions.